[ticket/12870] phpbbcli.php db:migrate can not update from 3.0.12 to 3.1

https://tracker.phpbb.com/browse/PHPBB3-12870

PHPBB3-12870
Duplication https://github.com/phpbb/phpbb/blob/develop-ascraeus/phpBB/install/database_update.php#L182
This should be a method on the migrator instead?