Fix dunder-method positional-only parameter discrepancies in third-party stubs (#14529)

stubs/gevent/gevent/local.pyi

@@ -4,8 +4,8 @@ from typing_extensions import Self
 class local:
     def __init__(self, *args: object, **kwargs: object) -> None: ...
     def __copy__(self) -> Self: ...
-    def __getattribute__(self, name: str) -> Any: ...
-    def __delattr__(self, name: str) -> None: ...
-    def __setattr__(self, name: str, value: Any) -> None: ...
+    def __getattribute__(self, name: str, /) -> Any: ...
+    def __delattr__(self, name: str, /) -> None: ...
+    def __setattr__(self, name: str, value: Any, /) -> None: ...
 
 __all__ = ["local"]