Use typing_extensions.Self in the stdlib (#9694)

stdlib/urllib/response.pyi

@@ -1,20 +1,21 @@
 import sys
-from _typeshed import ReadableBuffer, Self
+from _typeshed import ReadableBuffer
 from collections.abc import Callable, Iterable
 from email.message import Message
 from types import TracebackType
 from typing import IO, Any, BinaryIO
+from typing_extensions import Self
 
 __all__ = ["addbase", "addclosehook", "addinfo", "addinfourl"]
 
 class addbase(BinaryIO):
     fp: IO[bytes]
     def __init__(self, fp: IO[bytes]) -> None: ...
-    def __enter__(self: Self) -> Self: ...
+    def __enter__(self) -> Self: ...
     def __exit__(
         self, type: type[BaseException] | None, value: BaseException | None, traceback: TracebackType | None
     ) -> None: ...
-    def __iter__(self: Self) -> Self: ...
+    def __iter__(self) -> Self: ...
     def __next__(self) -> bytes: ...
     def close(self) -> None: ...
     # These methods don't actually exist, but the class inherits at runtime from