ci(workflow): update actions/stale to v6

.github/workflows/stale.yml

@@ -18,7 +18,7 @@ jobs:
       pull-requests: write
 
     steps:
-    - uses: actions/stale@v3
+    - uses: actions/stale@v6
       with:
         repo-token: ${{ secrets.GITHUB_TOKEN }}
         stale-issue-message: 'This issue has not seen any action for a while! Closing for now, but it can be reopened at a later date.'