Add action to check PR labels (#2469)

* Check PR labels

* update

* update

* update

* only use lable events

* remove env stuff

* add back types

.github/workflows/check_pr_labels.yml

@@ -0,0 +1,19 @@
+name: Check PR
+
+on:
+  pull_request:
+    branches: ["main"]
+    types: [opened, synchronize, reopened, labeled, unlabeled]
+
+jobs:
+  init:
+    name: Check labels
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check labels
+        run: |
+          labels=$(jq -r '.pull_request.labels[] | .name' ${{github.event_path }})
+          echo "$labels"
+          if [ "$labels" == "cla-signed" ]; then
+            exit 1
+          fi