This adds:
- GitHub actions,
- tox configuration,
- pre-commit hook, and
- makefile rules
to run blacken-docs linter.
Co-authored-by: David Smith <smithdc@gmail.com>
This pins Sphinx version, because the default Sphinx version used by
RTD is not compatible with Python 3.8+.
This also, sets Python 3.8 for RTD builds which is compatible with all
current versions of Django.
Thanks to Mariusz Felisiak for the suggestion.