Consider adding pyrefly as a type checker in addition to mypy

[WilliamJamieson]

Pyrefly has recently released a stable version 1.0, see announcement. It seems like a promising alternative to mypy that is now production ready.

[henryiii]

Does it have an integration with... Ah, found it:

https://github.com/facebook/pyrefly-pre-commit

Yes, should be easy then.

(I saw the announcement at a booth at PyCon. ;) )