Docs no longer building

[ianmkenney]

The scheduled CI and PR CI are failing due to docs not building. This happened in the hole2-mdakit due to Sphinx 7. The quick fix is to pin the version of sphinx to a working one.

We should probably address this properly though since all MDAKits generated from the cookiecutter will probably fail in the same way.

[lilyminium]

Ok, I'm a bit mystified by this. The error is:

preparing documents... done
writing output... [ 12%] cookiecutter/hooks
Theme error:
An error happened in rendering the page cookiecutter/hooks.
Reason: UndefinedError("'style' is undefined")

There's nothing special about hooks that I can tell, just that it's the first to be rendered. This is clearly because of sphinx-doc/sphinx#11381 , but I can't see that we use the style or styles keyword anywhere, or in sphinx_rtd_theme (just from a ctrl+f through its repo). That being said, changing from sphinx_rtd_theme to anything else does allow docs to build, so it could be something there. We should definitely revisit this but I vote for pinning sphinx lower for now.

(I've also tried various combinations of commenting or setting style, styles, html_style, etc in conf.py and nothing changed.)

[ianmkenney]

Agreed, I think pinning is a good option until we know more.