This Github workflow will add 'not stale' label on copybara PR's (#4406)

.github/workflows/labeler.yml

@@ -0,0 +1,21 @@
+# This workflow adds the "not stale" label to all PRs opened by copybara-service[bot] so that these are skipped from the stale workflow 
+#
+# You can adjust the behavior by modifying this file.
+# For more information, see:
+# https://github.com/actions-ecosystem/action-add-labels
+name: Add label to copybara-service PRs
+
+on:
+  pull_request:
+    types: opened
+
+jobs:
+  add_labels:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@main
+      - uses: actions-ecosystem/action-add-labels@v1
+        if: github.actor == 'copybara-service[bot]'
+        with:
+          labels: not stale
+          debug-only: true