Fix positional-only differences in many stdlib modules (#7226)

stdlib/argparse.pyi

@@ -322,7 +322,7 @@ if sys.version_info >= (3, 9):
 class Namespace(_AttributeHolder):
     def __init__(self, **kwargs: Any) -> None: ...
     def __getattr__(self, name: str) -> Any: ...
-    def __setattr__(self, name: str, value: Any) -> None: ...
+    def __setattr__(self, __name: str, __value: Any) -> None: ...
     def __contains__(self, key: str) -> bool: ...
 
 class FileType: