annotate pathlib.Path.{owner,group,is_mount} on windows

[jorenham]

This basically is uses the same partytrick as #13602, but applied to Never itself, and leads to similar issues in the NumPy stubs, as well.

Attempting to use these methods on windows <3.12 will now be reported by mypy as a classic misc, instead of attr-defined, which IMO was a bit more confusing.
Pyright users won't even notice the difference — they'll still be confronted with very same reportAttributeAccessIssue and reportUnknownMemberType power chords.

[github-actions]

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

[srittau]

Interesting approach. I like this, because it reduces the number of stubtest ignore entries, while documenting the problem better in the stub itself. But wouldn't it be better to just annotate these methods to return NoReturn instead of using the self: Never hack?

[jorenham]

But wouldn't it be better to just annotate these methods to return NoReturn instead of using the self: Never hack?

I thought about that, and I've tried it before. But this has three problems:

1. Mypy doesn't report it as invalid
2. Mypy won't analyze the code than "comes after" it, but doesn't tell that, which is problematic when type-testing it using .pyi
3. Subclasses won't be able to override this method as that would violate LSP (only relevant on Python 3.12 in this case)