Add automerge workflow (#36)

* Add automerge workflow

* Update automerge.yml

* Update automerge.yml

.github/workflows/automerge.yml

@@ -0,0 +1,25 @@
+---
+name: Automerge
+
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  merge:
+    name: Merge #${{ number }}
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    if: github.actor == 'dependabot[bot]'
+    steps:
+      - name: Approve pull request
+        run: gh pr review --approve "$PR_URL"
+        env:
+          PR_URL: ${{ github.event.pull_request.html_url }}
+          GH_TOKEN: ${{ secrets.GH_TOKEN }}
+      - name: Merge pull request
+        run: gh pr merge --auto --merge "$PR_URL"
+        env:
+          PR_URL: ${{ github.event.pull_request.html_url }}
+          GH_TOKEN: ${{ secrets.GH_TOKEN }}