Makes room for moderators between users and admins. It adds users.role,
which replaces the is_admin flag, and 0005 then drops the flag.
f
up(db: DatabaseSync): void
Run once by runMigrations. Every user becomes a user, except those with
is_admin set, who become admins.
Usage
import * as mod from "api/db/migrations/0004_user_roles.ts";