db: only use `AutoMigrate` to create new tables (#6092)
db: only use `AutoMigrate` to create new tables (#6092)

* Only use AutoMigrate to create new tables

* Revert models.go
mukaiu/gogs,mukaiu/gogs,chriswatt/gogs,chriswatt/gogs,mukaiu/gogs,gogits/gogs,chriswatt/gogs,gogits/gogs,gogits/gogs