Add close inactive issue workflow/action

[madeline-scyphers]

https://docs.github.com/en/actions/use-cases-and-examples/project-management/closing-inactive-issues
https://github.com/marketplace/actions/close-stale-issues

Close out inactive/stale issues automatically.

• We need to decide on good defaults.
  • @jmikayla1991, I would recommend long time scales since this is a repo maintained by a low number of people at a time. Maybe wait somewhere between 6 months - 1 year of no activity before posting the warning (warning is that if no further activity after X time, then issue will be closed), and then X time could be 1 -3 months (if no further activity after somewhere between 1-3 months, it gets closed automatically)