Move typing_extensions to stdlib (#5233)

I'm not sure what the best way to do this is. This effectively orphans
types-typing-extensions, but maybe that's not really a problem. (We can
yank the package too)

See https://github.com/python/typeshed/pull/5229#issuecomment-822234125
for some details

Co-authored-by: hauntsaninja <>

tests/stubtest_whitelists/py3_common.txt

@@ -307,6 +307,7 @@ collections.abc.*  # Types are re-exported from _collections_abc, so errors shou
 tempfile._TemporaryFileWrapper.[\w_]+
 # Various classes in typing aren't types at runtime. In addition, mypy thinks some special forms are tautologically defined.
 typing.[A-Z]\w+
+typing_extensions\..*
 # We can't distinguish not having a default value from having a default value of inspect.Parameter.empty
 inspect.Parameter.__init__
 inspect.Signature.__init__