Add PR checks (#673)

Author: fgreinacher

.github/workflows/pr.yml

@@ -0,0 +1,15 @@
+name: "Pull Request"
+on:
+  pull_request_target:
+    types:
+      - opened
+      - edited
+      - synchronize
+jobs:
+  main:
+    name: Check PR title
+    runs-on: ubuntu-latest
+    steps:
+      - uses: amannn/action-semantic-pull-request@v1.2.0
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}