Fix type ignore

Author: srittau

stdlib/builtins.pyi

@@ -192,7 +192,7 @@ class type:
     def __basicsize__(self) -> int: ...
     # type.__dict__ is read-only at runtime, but that can't be expressed currently.
     # See https://github.com/python/typeshed/issues/11033 for a discussion.
-    __dict__: Final[types.MappingProxyType[str, Any]]  # type: ignore[override]
+    __dict__: Final[types.MappingProxyType[str, Any]]  # type: ignore[assignment]
     @property
     def __dictoffset__(self) -> int: ...
     @property