.github/workflows: Add a workflow for dealing with stale issues/prs

[the-maldridge]

This PR adds the stale action to try and keep an eye on things that are stale due to inactivity. It will not act on any PR or issue that is assigned. Right now it won't even make any changes, I just want it to run so we can evaluate what the rough impact would be of switching on a stale PR minder.

[ahesford]

We know at least some people don't respond to manual pings on long-inactive PRs and a fair number of distro-hoppers will respond that they no longer use Void and don't care about the request. This seems like an effective way to deal with those would-be-abandonware packages.

[0x5c]

This would essentially take care of #36253 fully

[subnut]

I guess we could tag the stale PRs with the "stale-pending_reply" tag, and ping the author requesting him to reply if they are still interested. Then wait for a specified time period (3 weeks?)

• If they reply, remove the stale-pending_reply tag
• If they do not reply, remove the stale-pending_reply, add the stale tag
  • Wait again for some time period
  • If author replies within said time period, remove stale tag
  • If time period ends without author replying, close the PR

EDIT: It's all speculation for the future. I don't even know if GitHub API allows this.
EDITv2: 🤦 I hadn't even seen the files added by this PR before making this comment

[classabbyamp]

i believe that's what the stale action in this automates. maybe not the exact method but the overall concept

[Chocimier]

Closing PRs is fine, but reported bugs don't go away just because they are old. Issues should be rather marked as stale and left open.

Ok for dry run.

[0x5c]

Closing PRs is fine, but reported bugs don't go away just because they are old. Issues should be rather marked as stale and left open.

Ok for dry run.

Oh yeah issues should probably not be auto-closed
A review of the issue backlog seems to be in order tho