Documentation cannot be generated with Sphinx 4.*

[Matěj Cepl]

[ 26s] + python3 setup.py build_sphinx
[ 26s] running build_sphinx
[ 26s] Running Sphinx v4.0.2
[ 26s] /usr/lib/python3.8/site-packages/setuptools/dist.py:691: UserWarning: Usage of dash-separated 'description-file' will not be supported in future versions. Please use the underscore name 'description_file' instead
[ 26s] warnings.warn(
[ 26s] /usr/lib/python3.8/site-packages/setuptools/dist.py:691: UserWarning: Usage of dash-separated 'author-email' will not be supported in future versions. Please use the underscore name 'author_email' instead
[ 26s] warnings.warn(
[ 26s] /usr/lib/python3.8/site-packages/setuptools/dist.py:691: UserWarning: Usage of dash-separated 'home-page' will not be supported in future versions. Please use the underscore name 'home_page' instead
[ 26s] warnings.warn(
[ 26s] /usr/lib/python3.8/site-packages/setuptools/dist.py:691: UserWarning: Usage of dash-separated 'description-file' will not be supported in future versions. Please use the underscore name 'description_file' instead
[ 26s] warnings.warn(
[ 26s] /usr/lib/python3.8/site-packages/setuptools/dist.py:691: UserWarning: Usage of dash-separated 'author-email' will not be supported in future versions. Please use the underscore name 'author_email' instead
[ 26s] warnings.warn(
[ 26s] /usr/lib/python3.8/site-packages/setuptools/dist.py:691: UserWarning: Usage of dash-separated 'home-page' will not be supported in future versions. Please use the underscore name 'home_page' instead
[ 26s] warnings.warn(
[ 26s]
[ 26s] Configuration error:
[ 26s] There is a syntax error in your configuration file: invalid syntax (conf.py, line 185)

When building documentation with Sphinx 4.0.2 I get this error. Documentation builds perfectly well with Sphinx 2.3.1.

[Steve Kowalik (stevenk)]

This is a trivial patch to support Sphinx >= 3.