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

stdlib/_weakref.pyi

@@ -23,7 +23,6 @@ class ReferenceType(Generic[_T]):
     __callback__: Callable[[ReferenceType[_T]], Any]
     def __new__(cls: type[Self], o: _T, callback: Callable[[ReferenceType[_T]], Any] | None = ...) -> Self: ...
     def __call__(self) -> _T | None: ...
-    def __hash__(self) -> int: ...
     if sys.version_info >= (3, 9):
         def __class_getitem__(cls, item: Any) -> GenericAlias: ...