Context: my /usr/bin/python3 is 3.6. I've also tried with 3.7 and 3.8. I've tried it with venvs and without.

There are a number of problems here:

• Makefile hard-codes $(PYTHON) to /usr/bin/python3
• there is no way to specify which python executable I want to use (e.g. passing the "PYTHON" variable to make)
• make lint fails (assignment expressions)
• make sphinx fails (no "from future import __annotations__", missing "from future" statements, no str.removeprefix, no __class_getitem__)
• we are running pre-commit rather than `$(PYTHON) -m pre_commit
• CI hides these problems

I would expect to be able to do all of the above using older Python versions. 3.8+ would be good, but 3.6+ would be better.