Declare frozendict equality and inequality methods (#16795)

Author: carljm

stdlib/builtins.pyi

@@ -1420,6 +1420,8 @@ if sys.version_info >= (3, 15):
         def __getitem__(self, key: _KT, /) -> _VT_co: ...
         def __reversed__(self) -> Iterator[_KT]: ...
         def __iter__(self) -> Iterator[_KT]: ...
+        def __eq__(self, value: object, /) -> bool: ...
+        def __ne__(self, value: object, /) -> bool: ...
         def __hash__(self) -> int: ...
         def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
         def __or__(self, value: dict[_T1, _T2] | frozendict[_T1, _T2], /) -> frozendict[_KT | _T1, _VT_co | _T2]: ...