Deprecate passing file paths instead of URLs to `mimetypes.guess_type()`

Feature or enhancement

Proposal:

In Python 3.13, mimetypes.guess_file_type() was introduced as the preferred alternative to guess_type() for file paths. The documentation was updated with a .. soft-deprecated:: 3.13 note at the time.

However, the # TODO: Deprecate accepting file paths (in particular path-like objects) comment in Lib/mimetypes.py was never fulfilled, and no actual DeprecationWarning is currently emitted at runtime when paths are passed in.

This proposal is to fulfill the existing # TODO and emit a DeprecationWarning for passing plain strings (with no valid URL scheme), bytes, and os.PathLike objects into mimetypes.guess_type().

This completes the soft-deprecation cycle initiated in Python 3.13.

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

This fulfills the existing # TODO added during the introduction of guess_file_type() in Python 3.13:
https://github.com/python/cpython/blob/main/Lib/mimetypes.py#L131

Linked PRs

• gh-151576

Start in Lib/mimetypes.py at the existing TODO and inspect guess_type() alongside guess_file_type(). Verify the intended warning behavior for plain path strings, bytes, and os.PathLike inputs while preserving URL handling; the work is complete when the deprecation warning is covered and the existing behavior remains correct.