workflows: add a job to check commit messages

Signed-off-by: John Mulligan <jmulligan@redhat.com>

.github/workflows/ci.yml

@@ -10,6 +10,19 @@ on:
     - cron: 1 1 * * *
 
 jobs:
+  check-commits:
+    runs-on: ubuntu-latest
+    if: github.event_name == 'pull_request'
+    steps:
+    - uses: actions/checkout@v3
+      with:
+        fetch-depth: 0
+        ref: ${{ github.event.pull_request.head.sha }}
+    - uses: actions/setup-python@v4
+    - name: Install tox
+      run: python -m pip install tox
+    - name: Run gitlint
+      run: tox -e gitlint
   test:
     runs-on: ubuntu-latest
     steps: