How to support 'unique_together'

[LuoLuo0101]

class RoleMenu(orm.Model):
tablename = "role_menu"
registry = registry_main

fields = {
    "id": orm.BigInteger(primary_key=True),
    "role_id": orm.BigInteger(index=True),
    "menu_id": orm.BigInteger(index=True),
    "is_active": orm.Boolean(default=False),
    "is_new": orm.Boolean(default=True),
}
# unique_together = (("role_id", "menu_id"),)

[SepehrBazyar]

Hi
I needed this feature in this project, therefore in this PR I tried to implement it.
I would really appreciate it if you take a look.
Thank you!