Add step to approve Dependabot pull request

Author: lulunac27a

.github/workflows/dependabot-merge.yml

@@ -15,6 +15,11 @@ jobs:
         uses: dependabot/fetch-metadata@v2
         with:
           github-token: "${{ secrets.GITHUB_TOKEN }}"
+      - name: Approve a PR
+        run: gh pr review --approve "$PR_URL"
+        env:
+          PR_URL: ${{github.event.pull_request.html_url}}
+          GH_TOKEN: ${{secrets.GITHUB_TOKEN}}
       - name: Enable auto-merge for Dependabot PRs
         run: gh pr merge --auto --merge "$PR_URL"
         env: