Get rid of username notification checker in merge commit messages

[bncer]

Closes #455

Github is going to implement this feature on December 8th.

So it should work now and when I run on test repo I got a notification from commit message and an email received: [bncer/boring-test] Check if notification from @opendatavibe happens (2592771) Inbox [email protected] Unsubscribe 00:34 (13 minutes ago)

[Kobzol]

Thanks! I'll leave this open until December, if you don't mind, just in case GitHub changes their minds...

[bncer]

Sure

[Kobzol]

Looks like nothing changed from GitHub's side, let's go ahead with this. Thank you!