I am running a stellar private network with core version 12 and horizon version 20.0.1 Now I need to upgrade the core and horizon both from core version 12 to 15.0.0 and horizon 20.0.1 to 1.11.0 . In database there are few changes in stellar-core 15 and horizon 1.11 . In my stellar-core version 12, it has data and ledgers, so in this case how would I migrate the core and horizon.