gh-157763: Soft-deprecate ctypes.util.test

[ZeroIntensity]

• Issue: ctypes.util.test() calls cdll.load, which LibraryLoader does not have #157763

[ZeroIntensity]

@hugovk Any idea what's wrong with the lint job? The code that Ruff is complaining about is unrelated to this PR.

[BHUVANSH855]

I think dllist is still intentionally reexported as ctypes.util.dllist, removing test() only removed its last in-module reference, so ruff now reports F401.

[ZeroIntensity]

Hm, okay. Why is Ruff linting ctypes at all? I thought the lint jobs were supposed to be limited to a specific list of modules, because the stdlib is chock full of weird things that linters don't like.

[hugovk]

@hugovk Any idea what's wrong with the lint job? The code that Ruff is complaining about is unrelated to this PR.

Error: Lib/ctypes/util.py:419:25: F401 `_ctypes.dllist` imported but unused; consider using `importlib.util.find_spec` to test for availability

You've deleted code that used the import, so delete the import as well.

[hugovk]

Hm, okay. Why is Ruff linting ctypes at all? I thought the lint jobs were supposed to be limited to a specific list of modules, because the stdlib is chock full of weird things that linters don't like.

We only lint for unused imports (F401) in the stdlib:

#151478

Before this, we've had lots of PRs to remove unused imports:

https://github.com/python/cpython/pulls?q=is%3Apr+state%3Aclosed+%22remove+unused+imports%22

It's often an easy little performance improvement, keeps the code tidier, and lint lets us avoid them in the first place.