[7.16.5] Building project documentation with Sphinx: ValueError: Unsupported mimetype

[frenzymadness]

I'm trying to update the RPM package in Fedora Linux which also builds documentation for the nbconvert project.

I'm getting the following error:

+ sphinx-build-3 docs/source html
Running Sphinx v7.3.7

Exception occurred:
  File "/builddir/build/BUILD/python-nbconvert-7.16.5-build/nbconvert-7.16.5/nbconvert/exporters/templateexporter.py", line 667, in get_template_names
    raise ValueError(msg)
ValueError: Unsupported mimetype 'text/x-rst' for template 'rst', mimetypes supported are: 
        text/restructuredtext

It seems that the mime type has been changed in #2167. The documentation build in Github Actions works fine, but it might be caused by the quite old version of Sphinx (5.0.2 from Jun 2022) used in the CI. We use version 7.3.7 and we'll soon update to version 8.

[frenzymadness]

As far as I can tell this problem blocks also documentation builds of dependant packages like nbsphinx and OWSlib.

[krassowski]

CC @takluyver as author of #2167