Speed up `pathlib.PurePath.[is_]relative_to()`

[barneygale]

Both methods call self.with_segments() unconditionally. This can be skipped if the other argument is already an instance of PurePath, and no further (deprecated) positional arguments are given.

Also, relative_to() can inline the core of the is_relative_to() check to avoid the type/deprecated args checks.

Linked PRs

• GH-111429: Speed up pathlib.PurePath.[is_]relative_to() #111431

[barneygale]

Resolved in 3.13 / 6e93540 / #111431