[Chore] Update stale workflow to include PRs (#27918)

Author: kodster28

.github/workflows/close-stale-issues-prs.yml

@@ -23,4 +23,9 @@ jobs:
           days-before-stale: 35
           # setting to a negative number means they'll never be autoclosed
           days-before-close: -1
+          # we are okay with PRs being auto-closed
+          days-before-pr-close: 25
+          exempt-pr-labels: "never-stale"
+          close-pr-message: "Hey there, we've closed out this pull request because it's been stale for a while and there's been no additional action on it. If these changes are still relevant, open a new pull request (or flag to us in a GitHub issue)."
+          close-pr-label: "closed-as-stale"
           operations-per-run: 100