add checkout

Author: Patrick Schwager

.github/workflows/dependabot-automerge.yml

@@ -15,6 +15,8 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.actor == 'dependabot[bot]' }}
     steps:
+      - name: Checkout
+        uses: actions/checkout@v4.2.2
       - name: Approve Dependabot PRs
         run: gh pr review --approve "$PR_URL"
         env: