Team is notified when a new contributor posts a comment to a GitHub issue

[MisRob]

Observed behavior

From time to time, we miss a comment from a new contributor. Typically, they usually ask if they can pick up a particular issue in that issue's comments. Even though we have a Slack channel connected to all GitHub events, that doesn't seem to work well because there's lots of activity and it's easy to miss something. It'd be nice if the team could be notified when someone who's not in the core team posts a comment so we can be more certain that we reply.

A GitHub action may be handy for this purpose:

One other possibility is to create a github action to alert us to first time or external contributor comments. First time is relatively easy to detect and is probably the highest priority. (~ @rtibbles)