Fix one overload

Author: srittau

stdlib/functools.pyi

@@ -190,11 +190,6 @@ class partialmethod(Generic[_T]):
     def __isabstractmethod__(self) -> bool: ...
     def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
 
-if sys.version_info >= (3, 11):
-    _RegType: TypeAlias = type[Any] | types.UnionType
-else:
-    _RegType: TypeAlias = type[Any]
-
 @type_check_only
 class _SingleDispatchCallable(Generic[_P, _T]):
     # First argument pf the callables in the registry is the type to dispatch on.
@@ -225,7 +220,7 @@ class _SingleDispatchCallable(Generic[_P, _T]):
         ) -> Callable[Concatenate[_S, _P], _T]: ...
     # fun.register(int, lambda x: x)
     @overload
-    def register(self, cls: _RegType, func: Callable[Concatenate[_S, _P], _T]) -> Callable[Concatenate[_S, _P], _T]: ...
+    def register(self, cls: type[_S], func: Callable[Concatenate[_S, _P], _T]) -> Callable[Concatenate[_S, _P], _T]: ...
     def _clear_cache(self) -> None: ...
     def __call__(self, arg: object, /, *args: _P.args, **kwargs: _P.kwargs) -> _T: ...