Update typing_extensions imports in stdlib (#11244)

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

stdlib/distutils/cygwinccompiler.pyi

@@ -1,7 +1,7 @@
 from distutils.unixccompiler import UnixCCompiler
 from distutils.version import LooseVersion
 from re import Pattern
-from typing_extensions import Literal
+from typing import Literal
 
 def get_msvcr() -> list[str] | None: ...
 

stdlib/distutils/filelist.pyi

@@ -1,7 +1,6 @@
 from collections.abc import Iterable
 from re import Pattern
-from typing import overload
-from typing_extensions import Literal
+from typing import Literal, overload
 
 # class is entirely undocumented
 class FileList:

stdlib/distutils/util.pyi

@@ -1,7 +1,6 @@
 from _typeshed import StrPath, Unused
 from collections.abc import Callable, Container, Iterable, Mapping
-from typing import Any
-from typing_extensions import Literal
+from typing import Any, Literal
 
 def get_host_platform() -> str: ...
 def get_platform() -> str: ...