Support new Sphinx releases

[jsorva]

AFAIK, a-plus-rst-tools supports Sphinx up to version 4, which is years old by now. At the time of writing, the newest Sphinx release is 7.3. (The Sphinx changelog is here.) Supporting newer Sphinx versions soon would be great.

(Also, I’m not sure if newer versions of Python even work with old Sphinx versions like 4.1. At least I had some trouble with this when I tried. Presumably folks are gradually moving to new Python versions.)

Some observations based on quick local experiments with my O1 course materials:

• Supporting Sphinx versions up to 6.2.1 looks unproblematic (at least as far as my materials are concerned). There are a few small changes to HTML output that teachers (such as I) who use custom css/js need to check.
• Supporting Sphinx 7.0.0 and up means a tiny change would be needed in conf.py files and the theme template, because the style key has been replaced by styles.
• Supporting Sphinx 7.2.0 and up requires some more effort. Specifically, what happened when I tried using a-plus-rst-tools with Sphinx 7.2 (and 7.3) was this:
  • toc_config.py gives warnings that say something like "Starting from Sphinx 8, it won’t be OK to handle paths as strings — use Path objects instead".
  • Moreover, even through those warnings were apparently intended as mere advance warnings about the upcoming Sphinx 8, toc_config.py actually crashes with a path-related error (that I didn’t examine more closely).

[jsorva]

There is a related but somewhat obsolete issue here: #151