markdown: remove __getattr__() (#7962)

Author: lucas-six

stubs/Markdown/markdown/util.pyi

@@ -54,5 +54,3 @@ class Registry:
     def __setitem__(self, key: str, value: Any) -> None: ...
     def __delitem__(self, key: str) -> None: ...
     def add(self, key: str, value: Any, location: str) -> None: ...
-
-def __getattr__(name): ...