Ping assignee if tickets are assigned and author if not

This is a reply to gitlab#23 (comment 2872013). If a ticket is assigned to someone pinging the assignee seems like the thing to do. If not then reminding the author of the ticket to get it moved forward (i.e. assigned to someone or moved to Icebox or something) sounds reasonable to me. I can see that being annoying in case the author does not have the power to do ticket assignment/label adjustments etc. but I think that would still be okay. They could ping someone with those powers to move the issue forward on their behalf or just get that fixed together with the triage owner.