Add better types for predicate parameter to inspect.getx functions

[Gobot1234]

No description provided.

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[AlexWaygood]

I checked out this PR branch locally, and tried adding this test case to a new test_cases/stdlib/check_inspect.py file:

from __future__ import annotations

import inspect
from typing import Any, List, Tuple
from typing_extensions import TypeGuard, assert_type

def foo(obj: Any) -> TypeGuard[list[str]]:
    return isinstance(obj, list) and all(isinstance(item, str) for item in obj)

class Bar: ...
x = Bar()

assert_type(inspect.getmembers(x), List[Tuple[str, Any]])
assert_type(inspect.getmembers(x, None), List[Tuple[str, Any]])
assert_type(inspect.getmembers(x, foo), List[Tuple[str, List[str]]])

It seems to pass pyright, but the last assertion fails on mypy (mypy infers list[tuple[str, Any]] for all three). I guess this is just because pyright has better handling of generic TypeGuards in this situation?

[AlexWaygood]

I verified that this is a clear improvement for pyright users, and it doesn't lead to any regressions for mypy users (mypy users just won't get the same benefits right now). So I'm happy for this to go in.