What I did is editing the file src/XF/Db/Schema/Column.php.
On line 586, I replaced:
if ($type == 'enum' && isset($matches))
if (($type == 'enum' || $type == 'set') && isset($matches))
Though I asked xF to confirm my understanding.
It has worked apparently so you could be doing that, though I came into another bug into my code so you should be waiting for me to release a new version in a few minutes, apply the above and try upgrading.