Update typing_extensions imports in stdlib (#11244)

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

stdlib/tkinter/tix.pyi

@@ -1,7 +1,6 @@
 import tkinter
 from _typeshed import Incomplete
-from typing import Any
-from typing_extensions import Literal
+from typing import Any, Literal
 
 WINDOW: Literal["window"]
 TEXT: Literal["text"]