Description of problem:
Package python-sphinxygen fails to build from source in Fedora Rawhide.

Version-Release number of selected component (if applicable):
1.0.10-1.fc42

Steps to Reproduce:
fedspkg build

...
============================= test session starts ==============================
platform linux -- Python 3.13.3, pytest-8.3.5, pluggy-1.5.0
rootdir: /builddir/build/BUILD/python-sphinxygen-1.0.10-build/sphinxygen-v1.0.10
configfile: pyproject.toml
collected 1 item
test/test_sphinxygen.py F                                                [100%]
=================================== FAILURES ===================================
_________________________ TestSphinxygen.test_generate _________________________
self = <test.test_sphinxygen.TestSphinxygen testMethod=test_generate>
    def test_generate(self):
        self._run(["mkdir", "-p", "build"])
        self._run(["cp", "test/c/conf.py", "build"])
        self._run(["cp", "test/c/index.rst", "build"])
>       self._run(["doxygen", "test/c/Doxyfile"])
test/test_sphinxygen.py:36: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
test/test_sphinxygen.py:24: in _run
    proc = subprocess.run(
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
input = None, capture_output = True, timeout = None, check = True
popenargs = (['doxygen', 'test/c/Doxyfile'],)
kwargs = {'encoding': 'utf-8', 'stderr': -1, 'stdout': -1}
process = <Popen: returncode: 1 args: ['doxygen', 'test/c/Doxyfile']>
stdout = ''
stderr = "/builddir/build/BUILD/python-sphinxygen-1.0.10-build/sphinxygen-v1.0.10/test/c/include/testlib.h:206: error: explicit link request to 'testlib_manifesto' could not be resolved (warning treated as error, aborting now)\n"
retcode = 1
    def run(*popenargs,
            input=None, capture_output=False, timeout=None, check=False, **kwargs):
        """Run command with arguments and return a CompletedProcess instance.
    
        The returned instance will have attributes args, returncode, stdout and
        stderr. By default, stdout and stderr are not captured, and those attributes
        will be None. Pass stdout=PIPE and/or stderr=PIPE in order to capture them,
        or pass capture_output=True to capture both.
    
        If check is True and the exit code was non-zero, it raises a
        CalledProcessError. The CalledProcessError object will have the return code
        in the returncode attribute, and output & stderr attributes if those streams
        were captured.
    
        If timeout (seconds) is given and the process takes too long,
         a TimeoutExpired exception will be raised.
    
        There is an optional argument "input", allowing you to
        pass bytes or a string to the subprocess's stdin.  If you use this argument
        you may not also use the Popen constructor's "stdin" argument, as
        it will be used internally.
    
        By default, all communication is in bytes, and therefore any "input" should
        be bytes, and the stdout and stderr will be bytes. If in text mode, any
        "input" should be a string, and stdout and stderr will be strings decoded
        according to locale encoding, or by "encoding" if set. Text mode is
        triggered by setting any of text, encoding, errors or universal_newlines.
    
        The other arguments are the same as for the Popen constructor.
        """
        if input is not None:
            if kwargs.get('stdin') is not None:
                raise ValueError('stdin and input arguments may not both be used.')
            kwargs['stdin'] = PIPE
    
        if capture_output:
            if kwargs.get('stdout') is not None or kwargs.get('stderr') is not None:
                raise ValueError('stdout and stderr arguments may not be used '
                                 'with capture_output.')
            kwargs['stdout'] = PIPE
            kwargs['stderr'] = PIPE
    
        with Popen(*popenargs, **kwargs) as process:
            try:
                stdout, stderr = process.communicate(input, timeout=timeout)
            except TimeoutExpired as exc:
                process.kill()
                if _mswindows:
                    # Windows accumulates the output in a single blocking
                    # read() call run on child threads, with the timeout
                    # being done in a join() on those threads.  communicate()
                    # _after_ kill() is required to collect that and add it
                    # to the exception.
                    exc.stdout, exc.stderr = process.communicate()
                else:
                    # POSIX _communicate already populated the output so
                    # far into the TimeoutExpired exception.
                    process.wait()
                raise
            except:  # Including KeyboardInterrupt, communicate handled that.
                process.kill()
                # We don't call process.wait() as .__exit__ does that for us.
                raise
            retcode = process.poll()
            if check and retcode:
>               raise CalledProcessError(retcode, process.args,
                                         output=stdout, stderr=stderr)
E               subprocess.CalledProcessError: Command '['doxygen', 'test/c/Doxyfile']' returned non-zero exit status 1.
/usr/lib64/python3.13/subprocess.py:577: CalledProcessError
----------------------------- Captured stderr call -----------------------------
sphinxygen test error: Command '['doxygen', 'test/c/Doxyfile']' returned non-zero exit status 1.
/builddir/build/BUILD/python-sphinxygen-1.0.10-build/sphinxygen-v1.0.10/test/c/include/testlib.h:206: error: explicit link request to 'testlib_manifesto' could not be resolved (warning treated as error, aborting now)
=========================== short test summary info ============================
FAILED test/test_sphinxygen.py::TestSphinxygen::test_generate - subprocess.Ca...
============================== 1 failed in 0.19s ===============================

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

Reproducible: Always