stale: Prevent marking issues as stale and only process labeled PRs

Also increase the limit to wait for 30 days before closing

stale workflow has no option on running on issues only

See actions/stale#1112

.github/workflows/stale.yml

@@ -12,6 +12,10 @@ jobs:
     - uses: actions/stale@v9
       with:
         repo-token:  ${{ secrets.FLATHUBBOT_TOKEN }}
-        stale-pr-message: "This PR hasn't received any updates in a year and will be automatically closed in 14 days. Feel free to re-open it if you plan to continue working on that pull request or think it deserves attention from Flathub admins"
-        days-before-stale: 365
-        days-before-close: 14
+        stale-pr-message: "This PR hasn't received any updates in a year and will be automatically closed in 30 days. Feel free to re-open it if you plan to continue working on that pull request or think it deserves attention from Flathub admins"
+        days-before-stale: -1
+        days-before-close: -1
+        days-before-pr-stale: 365
+        days-before-pr-close: 30
+        only-pr-labels: awaiting-changes,blocked,work-in-progress,awaiting-upstream
+        remove-pr-stale-when-updated: true