CI builds failing on Sphinx incompatible with Python 3.10

[jaraco]

@jaraco I see you tried to create a release but Github Actions workflow failed due to a test failure.

Thought you'd like to know that it would appear that it's an issue with sphinx being incompatible with Python 3.10 and apparently not an issue with the code of setuptools:
sphinx-doc/sphinx#9505 (comment)

I also found this fix for the line causing the type error seen in this repo's failed build:
sphinx-doc/sphinx@8b2031c
...but it doesn't seem to be in the latest stable sphinx release yet.

Originally posted by @darkvertex in #2712 (comment)

[jaraco]

In my opinion, sphinx-doc/sphinx#9562 is a better upstream issue to track.