Mark first argument of __[get|set|del]attr__ as str (#9245)

stubs/html5lib/html5lib/filters/base.pyi

@@ -4,4 +4,4 @@ class Filter:
     source: Any
     def __init__(self, source) -> None: ...
     def __iter__(self): ...
-    def __getattr__(self, name): ...
+    def __getattr__(self, name: str): ...

stubs/html5lib/html5lib/treewalkers/etree_lxml.pyi

@@ -36,7 +36,7 @@ class FragmentWrapper:
     text: Any
     tail: Any
     def __init__(self, fragment_root, obj) -> None: ...
-    def __getattr__(self, name): ...
+    def __getattr__(self, name: str): ...
     def getnext(self): ...
     def __getitem__(self, key): ...
     def __bool__(self) -> bool: ...