Update typing_extensions imports in stdlib (#11244)

Co-authored-by: AlexWaygood <alex.waygood@gmail.com>

stdlib/threading.pyi

@@ -4,8 +4,7 @@ from _thread import _excepthook, _ExceptHookArgs, get_native_id as get_native_id
 from _typeshed import ProfileFunction, TraceFunction
 from collections.abc import Callable, Iterable, Mapping
 from types import TracebackType
-from typing import Any, TypeVar
-from typing_extensions import final
+from typing import Any, TypeVar, final
 
 _T = TypeVar("_T")