typing: improve CaptureQueriesContext and test decorators in django.t…

[01-Harshit]

…est.utils

I have made things!

This PR improves Django type stubs by strengthening type hints and replacing private API usage, while keeping runtime behavior unchanged.

Changes:

1. Private API replacement:

• Replaced _SupportsContains with Iterable in CaptureQueriesContext to make type-checking safer.

2. Stronger callable typing:

• Updated _DecoratedTest, _C, new_checks, deployment_checks, and filter_func to Callable[..., Any] for better Mypy and Pyright support.

These improvements preserve runtime behavior while enhancing IDE autocomplete and type safety.

Verification:
Successfully ran: python -m mypy.stubtest django.test.utils

Output: Success: no issues found in 1 module

[UnknownPlatypus]

Updated _DecoratedTest, _C, new_checks, deployment_checks, and filter_func to Callable[..., Any] for better Mypy and Pyright support.

There is no typing improvement, these are equivalent. But it’s slightly better because it would pass mypy no_any_generic check.

However, can we have a more narrow type here or is this the only option?

[01-Harshit]

• Regarding Callable[..., Any], this change does not improve typing precision but satisfies mypy's no_any_generic check. Narrower typing is challenging because decorated functions can have varying signatures in Django.
• I believe this is the best practical balance between type safety and usability in this context.