[flake8-pyi]: PYI009, PYI010, PYI021 (#3230)
PYI009 and PYI010 are very similar, always use `...` in function and class bodies in stubs.
PYI021 bans doc strings in stubs.
I think all of these rules should be relatively straightforward to implement auto fixes for but can do that later once we get all the other rules added.
rel: https://github.com/charliermarsh/ruff/issues/848
