Move mypy to the end of pre-commit

[hoodmane]

Mypy is much slower than any of the other checks so it should go last.

[cclauss]

There is lots of talk about whether mypy should even be run in pre-commit:

• https://github.com/pre-commit/mirrors-mypy
• Difference between running mypy directly vs with pre-commit run -a pre-commit/pre-commit#1580
• https://jaredkhan.com/blog/mypy-pre-commit

I have started to remove if from pre-commit in projects but would be interested in your perspective.

[rth]

There is lots of talk about whether mypy should even be run in pre-commit:

Yeah, I also have mixed feelings about it, but probably would still tend to use pre-commit for it as,

• at least it's an env with fixed requirements that everyone uses, so much better for reproducibility.
• I don't want to manually run it for each commit. In our case, forgetting to fix mypy before pushing then doing something else burns hours of CI CPU time. Pre-commit provides some guardrails against doing that.