Fix assign-issue-action: revert to v2.2 (v3.0.0 is broken) (#11904)

v3.0.0 of takanome-dev/assign-issue-action is broken:
- action.yml references dist/index.js
- But the release only contains dist/index.mjs
- This causes immediate failure: "File not found: dist/index.js"

This PR:
1. Reverts to v2.2 which works correctly
2. Reverts reminder_days to 7 (v2.2 behavior: days before unassignment)
3. Adds comment with link to upstream bug report

Bug report: https://github.com/takanome-dev/assign-issue-action/issues/426

Fixes #11873

Co-authored-by: Hanan <okets78@hotmail.com>

.github/workflows/assign.yml

@@ -14,11 +14,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Assign the user or unassign stale assignments
-        uses: takanome-dev/assign-issue-action@3.0.0
+        # Note: v3.0.0 is broken (dist/index.mjs vs action.yml expects index.js)
+        # See: https://github.com/takanome-dev/assign-issue-action/issues/426
+        uses: takanome-dev/assign-issue-action@v2.2
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           maintainers: 'noisyfox,softfever'
           days_until_unassign: 30
           block_assignment: false
-          reminder_days: 20
+          reminder_days: 7
           max_assignments: 12