mypy

1741c16b - Use lower-case generics more consistently in error messages (#17035)

Use lower-case generics more consistently in error messages (#17035) Suggest `list[x]` instead of `List[x]` on Python 3.9 and later in hints. We already suggest `x | None` instead of `Optional[x]` on 3.10+, so this makes the error messages more consistent. Use lower-case `type[x]` when using `reveal_type` on Python 3.9 and later.