move generated stubs to separate directory, too messty

django-stubs-generated/db/migrations/operations/utils.pyi

@@ -0,0 +1,9 @@
+from typing import Any, Optional
+
+from django.db.migrations.state import ProjectState
+from django.db.models.fields import Field
+
+
+def is_referenced_by_foreign_key(
+    state: ProjectState, model_name_lower: str, field: Field, field_name: str
+) -> bool: ...