gh-85809: Ensure shutil.make_archive accepts path-like objects in all cases

[tadejmagajna]

This change ensures shutil.make_archive accepts path-like objects such as Pathlib.pathfor all parameters regardless of input. Includes lightweight tests and updated documentation with refreshed examples.

While shutil.make_archive did support Pathlib.path inputs in some cases, this behavior was undocumented, untested and resulted in an exception if root_dir was None. This case is well described in #94844 (comment).

This PR addresses the above issue following this suggested approach.

• Issue: make shutil.make_archive always accept pathlib objects #85809

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📚 Documentation preview 📚: https://cpython-previews--143668.org.readthedocs.build/

[tadejmagajna]

@serhiy-storchaka nicely described the suggested approach in #94844 (comment). Wondering if it is possible get a PR review for this.

[serhiy-storchaka]

I just tested -- directory descriptor is not supported as root_dir. So we do not need to worry about this.

As for the test -- currently it only tests that the zip archiver supports path-like arguments. We need something like test_make_archive_cwd_default, test_make_archive_cwd and test_make_archive_cwd_supports_root_dir to test format independent support. Register temporary a mock archiver, call make_archive() with path-like objects, and check what was passed to the archiver.

[tadejmagajna]

Thank you! Added the format-independent tests using the mock archiver pattern.

Covered all cases aside from test_make_archive_cwd which I believe isn't needed because when root_dir is passed to an archiver that doesn’t support it, the path is never forwarded, regardless of its type (which is already tested elsewhere).

Also added os.fspath() conversion for base_dir, which was previously missing.

[tadejmagajna]

Updated the branch with latest main to pick up a fix for an unrelated issue which was causing the CI to fail. @serhiy-storchaka happy to apply further changes once you are able to have a look.