Description of problem:
Package myst-nb fails to build from source in Fedora 43 and Rawhide.

Version-Release number of selected component (if applicable):
1.3.0-2.fc43

Steps to Reproduce:
koji build --scratch f44 myst-nb-1.3.0-2.fc43.src.rpm

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

Results:

________________ test_custom_convert_multiple_extensions_cache _________________
sphinx_run = <conftest.SphinxFixture object at 0xffff702bfb60>
file_regression = <conftest.FileRegression object at 0xffff70371630>
check_nbs = <function check_nbs.<locals>._check_nbs at 0xffff703a31c0>
    @pytest.mark.sphinx_params(
        "custom-formats2.extra.exnt",
        conf={
            "nb_execution_mode": "cache",
            "nb_custom_formats": {".extra.exnt": ["jupytext.reads", {"fmt": "Rmd"}]},
        },
    )
    def test_custom_convert_multiple_extensions_cache(
        sphinx_run, file_regression, check_nbs
    ):
        """The outputs should be populated."""
        sphinx_run.build()
        assert sphinx_run.warnings() == ""
>       regress_nb_doc(file_regression, sphinx_run, check_nbs)
/builddir/build/BUILD/myst-nb-1.3.0-build/MyST-NB-1.3.0/tests/test_execute.py:406: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/builddir/build/BUILD/myst-nb-1.3.0-build/MyST-NB-1.3.0/tests/test_execute.py:38: in regress_nb_doc
    file_regression.check(doctree_string, extension=".xml", encoding="utf-8")
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
self = <conftest.FileRegression object at 0xffff70371630>
data = '<document source="custom-formats2" translation_progress="{\'total\': 0, \'translated\': 0}">\n    <section ids="custo...0c7615e545fd.png" uri="_build/jupyter_execute/16cba4cd16990dd2051c7d78eafc4139cdbcb5ce4cc9aea85a670c7615e545fd.png">\n'
kwargs = {'encoding': 'utf-8', 'extension': '.xml'}
    def check(self, data, **kwargs):
>       return self.file_regression.check(self._strip_ignores(data), **kwargs)
E       AssertionError: FILES DIFFER:
E       /tmp/pytest-of-mockbuild/pytest-0/test_custom_convert_multiple_e1/test_custom_convert_multiple_extensions_cache.xml
E       /tmp/pytest-of-mockbuild/pytest-0/test_custom_convert_multiple_e1/test_custom_convert_multiple_extensions_cache.obtained.xml
E       HTML DIFF: /tmp/pytest-of-mockbuild/pytest-0/test_custom_convert_multiple_e1/test_custom_convert_multiple_extensions_cache.obtained.diff.html
E       --- 
E       +++ 
E       @@ -19,4 +19,4 @@
E                                <literal_block classes="output text_plain" language="myst-ansi" xml:space="preserve">
E                                    <Figure size 640x480 with 1 Axes>
E                            <container mime_type="image/png">
E       -                        <image candidates="{'*': '_build/jupyter_execute/79f662cf270a62ef0a2ed774bbb4eea8bc8701fbd0a79121fda9016aa2d3f034.png'}" uri="_build/jupyter_execute/79f662cf270a62ef0a2ed774bbb4eea8bc8701fbd0a79121fda9016aa2d3f034.png">
E       +                        <image candidates="{'*': '_build/jupyter_execute/16cba4cd16990dd2051c7d78eafc4139cdbcb5ce4cc9aea85a670c7615e545fd.png'}" uri="_build/jupyter_execute/16cba4cd16990dd2051c7d78eafc4139cdbcb5ce4cc9aea85a670c7615e545fd.png">
/builddir/build/BUILD/myst-nb-1.3.0-build/MyST-NB-1.3.0/tests/conftest.py:308: AssertionError
----------------------------- Captured stderr call -----------------------------
[IPKernelApp] WARNING | debugpy_stream undefined, debugging will not be enabled
=========================== short test summary info ============================
FAILED tests/test_execute.py::test_complex_outputs_unrun_cache - AssertionErr...
FAILED tests/test_execute.py::test_complex_outputs_unrun_auto - AssertionErro...
FAILED tests/test_execute.py::test_custom_convert_auto - AssertionError: FILE...
FAILED tests/test_execute.py::test_custom_convert_cache - AssertionError: FIL...
FAILED tests/test_execute.py::test_custom_convert_multiple_extensions_auto - ...
FAILED tests/test_execute.py::test_custom_convert_multiple_extensions_cache
=================== 6 failed, 81 passed in 115.79s (0:01:55) ===================