automatically add "waiting on review" label to new PRs

Author: syphar

.github/workflows/tag-new-pr.yml

@@ -0,0 +1,13 @@
+on:
+  pull_request_target:
+    branches:
+      - master
+    types: [opened, reopened]
+
+jobs:
+  update-labels:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions-ecosystem/action-add-labels@v1
+        with:
+          labels: S-waiting-on-review