test(migrations): satisfy pyrefly for dynamic module

Author: BeautyyuYanli

api/tests/unit_tests/migrations/test_remove_agent_drive.py

@@ -46,12 +46,12 @@ def _create_pre_upgrade_schema(engine: sa.Engine) -> None:
 def _run_migration_step(module: ModuleType, engine: sa.Engine, step_name: str) -> None:
     with engine.begin() as connection:
         operations = Operations(MigrationContext.configure(connection))
-        original_op = module.op
-        module.op = operations
+        original_op = module.__dict__["op"]
+        module.__dict__["op"] = operations
         try:
             getattr(module, step_name)()
         finally:
-            module.op = original_op
+            module.__dict__["op"] = original_op
 
 
 def test_upgrade_removes_agent_drive_schema_and_legacy_json_fields() -> None: