Remove un-needed __hash__ methods from stdlib (#8465)

stdlib/pathlib.pyi

@@ -38,7 +38,6 @@ class PurePath(PathLike[str]):
     @property
     def stem(self) -> str: ...
     def __new__(cls: type[Self], *args: StrPath) -> Self: ...
-    def __hash__(self) -> int: ...
     def __eq__(self, other: object) -> bool: ...
     def __fspath__(self) -> str: ...
     def __lt__(self, other: PurePath) -> bool: ...