add back labeler as v4

.github/workflows/labeler.yml

@@ -0,0 +1,17 @@
+name: "Pull Request Labeler"
+on:
+  - pull_request_target
+
+permissions:
+  contents: read
+
+jobs:
+  labeler:
+    permissions:
+      contents: read # for actions/labeler to determine modified files
+      pull-requests: write # for actions/labeler to add labels to PRs
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/labeler@v4
+        with:
+          repo-token: "${{ secrets.GITHUB_TOKEN }}"