When I restart spicedb, I find that the schema I defined earlier is missing! The command line I use: 1.spicedb serve --grpc-preshared-key "lx_token" --http-enabled --http-addr :3331 --grpc-addr :3332 --dashboard-addr :3333 --metrics-addr :3334 and 2.spicedb migrate head --datastore-engine mysql --datastore-conn-uri "root:123456@(localhost:3307)/my_spicedb?parseTime=True" is there any one who can answer this question?