chore: migrate type checking to ty

[DarkaMaul]

I've tried to remove our usage of mypy to use ty.
We just have some warnings when using stubs in our tests because they don't match the expected type, but I think that's expected.

[facutuesca]

Lint seems to still be failing

[DarkaMaul]

CI was failing because ty couldn't resolve pretend and pytest imports when running with INSTALL_EXTRA=lint (I don't know why mypy was not complaining though).

Interesting, I was ready to write that it was because I was running Python 3.12 on my laptop, and 3.14 on the CI, and my local tests with 3.14 (using uvx --python 3.14 ty check src test) were able also to show the CI behavior. But that's just because uvx starts from a clean env without dependencies

[facutuesca]

CI was failing because ty couldn't resolve pretend and pytest imports when running with INSTALL_EXTRA=lint (I don't know why mypy was not complaining though).

Looks like mypy was only running on the src directory:

[tool.mypy]
mypy_path = "src"

[DarkaMaul]

CI was failing because ty couldn't resolve pretend and pytest imports when running with INSTALL_EXTRA=lint (I don't know why mypy was not complaining though).

Looks like mypy was only running on the src directory:

[tool.mypy]
mypy_path = "src"

Good catch!