fix(test): add rateLimitTier to User mock in store db_test

The new rateLimitTier field on User is NOT NULL with a DB default,
so Prisma's Pydantic model requires it at construction time.

autogpt_platform/backend/backend/api/features/store/db_test.py

@@ -189,6 +189,7 @@ async def test_create_store_submission(mocker):
         notifyOnAgentApproved=True,
         notifyOnAgentRejected=True,
         timezone="Europe/Delft",
+        rateLimitTier="standard",
     )
     mock_agent = prisma.models.AgentGraph(
         id="agent-id",