Description of problem:
Package python-mplcairo fails to build from source in Fedora rawhide.

Version-Release number of selected component (if applicable):
0.3-4.fc33

Steps to Reproduce:
koji build --scratch f34 python-mplcairo-0.3-4.fc33.src.rpm

Additional info:
This package is tracked by Koschei. See:
https://koschei.fedoraproject.org/package/python-mplcairo

=================================== FAILURES ===================================
____________________________ test_specgram_fs_none _____________________________
[gw4] linux -- Python 3.9.1 /usr/bin/python3
    def test_specgram_fs_none():
        """Test axes.specgram when Fs is None, should not throw error."""
>       spec, freqs, t, im = plt.specgram(np.ones(300), Fs=None)
/usr/lib64/python3.9/site-packages/matplotlib/tests/test_axes.py:4155: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/usr/lib64/python3.9/site-packages/matplotlib/pyplot.py:2919: in specgram
    __ret = gca().specgram(
/usr/lib64/python3.9/site-packages/matplotlib/__init__.py:1427: in inner
    return func(ax, *map(sanitize_sequence, args), **kwargs)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
self = <AxesSubplot:>
x = array([1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1.,
       1., 1., 1., 1., 1., 1., 1., 1., 1., ...1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1.,
       1., 1., 1., 1., 1., 1., 1., 1., 1., 1., 1.])
NFFT = 256, Fs = 2, Fc = 0, detrend = None, window = None, noverlap = 128
cmap = None, xextent = None, pad_to = None, sides = None, scale_by_freq = None
mode = None, scale = 'dB', vmin = None, vmax = None, kwargs = {}
spec = array([[8.50000000e+01],
       [4.29996400e+01],
       [2.96562495e-04],
       [4.15570832e-05],
       [1.18056850... [1.45740501e-13],
       [8.18349917e-14],
       [3.63254653e-14],
       [9.07452846e-15],
       [0.00000000e+00]])
freqs = array([0.       , 0.0078125, 0.015625 , 0.0234375, 0.03125  , 0.0390625,
       0.046875 , 0.0546875, 0.0625   , 0.070...6875,
       0.9375   , 0.9453125, 0.953125 , 0.9609375, 0.96875  , 0.9765625,
       0.984375 , 0.9921875, 1.       ])
t = array([64.])
    @_preprocess_data(replace_names=["x"])
    @docstring.dedent_interpd
    def specgram(self, x, NFFT=None, Fs=None, Fc=None, detrend=None,
                 window=None, noverlap=None,
                 cmap=None, xextent=None, pad_to=None, sides=None,
                 scale_by_freq=None, mode=None, scale=None,
                 vmin=None, vmax=None, **kwargs):
        """
        Plot a spectrogram.
    
        Compute and plot a spectrogram of data in *x*.  Data are split into
        *NFFT* length segments and the spectrum of each section is
        computed.  The windowing function *window* is applied to each
        segment, and the amount of overlap of each segment is
        specified with *noverlap*. The spectrogram is plotted as a colormap
        (using imshow).
    
        Parameters
        ----------
        x : 1-D array or sequence
            Array or sequence containing the data.
    
        %(Spectral)s
    
        %(PSD)s
    
        mode : {'default', 'psd', 'magnitude', 'angle', 'phase'}
            What sort of spectrum to use.  Default is 'psd', which takes the
            power spectral density.  'magnitude' returns the magnitude
            spectrum.  'angle' returns the phase spectrum without unwrapping.
            'phase' returns the phase spectrum with unwrapping.
    
        noverlap : int
            The number of points of overlap between blocks.  The
            default value is 128.
    
        scale : {'default', 'linear', 'dB'}
            The scaling of the values in the *spec*.  'linear' is no scaling.
            'dB' returns the values in dB scale.  When *mode* is 'psd',
            this is dB power (10 * log10).  Otherwise this is dB amplitude
            (20 * log10). 'default' is 'dB' if *mode* is 'psd' or
            'magnitude' and 'linear' otherwise.  This must be 'linear'
            if *mode* is 'angle' or 'phase'.
    
        Fc : int, default: 0
            The center frequency of *x*, which offsets the x extents of the
            plot to reflect the frequency range used when a signal is acquired
            and then filtered and downsampled to baseband.
    
        cmap : `.Colormap`, default: :rc:`image.cmap`
    
        xextent : *None* or (xmin, xmax)
            The image extent along the x-axis. The default sets *xmin* to the
            left border of the first bin (*spectrum* column) and *xmax* to the
            right border of the last bin. Note that for *noverlap>0* the width
            of the bins is smaller than those of the segments.
    
        **kwargs
            Additional keyword arguments are passed on to `~.axes.Axes.imshow`
            which makes the specgram image.
    
        Returns
        -------
        spectrum : 2-D array
            Columns are the periodograms of successive segments.
    
        freqs : 1-D array
            The frequencies corresponding to the rows in *spectrum*.
    
        t : 1-D array
            The times corresponding to midpoints of segments (i.e., the columns
            in *spectrum*).
    
        im : `.AxesImage`
            The image created by imshow containing the spectrogram.
    
        See Also
        --------
        psd
            Differs in the default overlap; in returning the mean of the
            segment periodograms; in not returning times; and in generating a
            line plot instead of colormap.
        magnitude_spectrum
            A single spectrum, similar to having a single segment when *mode*
            is 'magnitude'. Plots a line instead of a colormap.
        angle_spectrum
            A single spectrum, similar to having a single segment when *mode*
            is 'angle'. Plots a line instead of a colormap.
        phase_spectrum
            A single spectrum, similar to having a single segment when *mode*
            is 'phase'. Plots a line instead of a colormap.
    
        Notes
        -----
        The parameters *detrend* and *scale_by_freq* do only apply when *mode*
        is set to 'psd'.
        """
        if NFFT is None:
            NFFT = 256  # same default as in mlab.specgram()
        if Fc is None:
            Fc = 0  # same default as in mlab._spectral_helper()
        if noverlap is None:
            noverlap = 128  # same default as in mlab.specgram()
        if Fs is None:
            Fs = 2  # same default as in mlab._spectral_helper()
    
        if mode == 'complex':
            raise ValueError('Cannot plot a complex specgram')
    
        if scale is None or scale == 'default':
            if mode in ['angle', 'phase']:
                scale = 'linear'
            else:
                scale = 'dB'
        elif mode in ['angle', 'phase'] and scale == 'dB':
            raise ValueError('Cannot use dB scale with angle or phase mode')
    
        spec, freqs, t = mlab.specgram(x=x, NFFT=NFFT, Fs=Fs,
                                       detrend=detrend, window=window,
                                       noverlap=noverlap, pad_to=pad_to,
                                       sides=sides,
                                       scale_by_freq=scale_by_freq,
                                       mode=mode)
    
        if scale == 'linear':
            Z = spec
        elif scale == 'dB':
            if mode is None or mode == 'default' or mode == 'psd':
>               Z = 10. * np.log10(spec)
E               RuntimeWarning: divide by zero encountered in log10
/usr/lib64/python3.9/site-packages/matplotlib/axes/_axes.py:7553: RuntimeWarning