Update typing_extensions imports in stdlib (#11244)

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

stdlib/sysconfig.pyi

@@ -1,6 +1,5 @@
 import sys
-from typing import IO, Any, overload
-from typing_extensions import Literal
+from typing import IO, Any, Literal, overload
 
 __all__ = [
     "get_config_h_filename",