unassign inactive users action

[SukhvirKooner]

Summary

This PR implements a GitHub Action to automatically unassign inactive issues based on a predefined period of inactivity. This action will help maintain cleaner issue assignments and prevent outdated issues from cluttering the project.

#12837

on:
  schedule:
    - cron: "1 0 * * 1" 
  workflow_dispatch:

Action is scheduled to run every monday at 00:01 UTC

[MisRob]

@rtibbles would you please set SLACK_COMMUNITY_NOTIFICATIONS_WEBHOOK_URL on this repo? Then we can merge.