Add automerge workflow

.github/workflows/automerge.yml

@@ -0,0 +1,46 @@
+name: automerge
+
+on:
+  pull_request:
+    types:
+      - labeled
+      - unlabeled
+      - synchronize
+      - unlocked
+  check_suite:
+    types:
+      - completed
+  status: {}
+
+jobs:
+  dependabot:
+    runs-on: ubuntu-latest
+    if: github.actor == 'dependabot[bot]' || github.actor == 'dependabot-preview[bot]'
+    steps:
+      -
+        name: Approve
+        uses: actions/github-script@0.9.0
+        with:
+          github-token: ${{secrets.GITHUB_TOKEN}}
+          script: |
+            await github.pulls.createReview({
+              owner: context.payload.repository.owner.login,
+              repo: context.payload.repository.name,
+              pull_number: context.payload.pull_request.number,
+              event: 'APPROVE'
+            })
+      -
+        name: Wait
+        run: sleep 3
+      -
+        name: Merge
+        uses: actions/github-script@0.9.0
+        with:
+          github-token: ${{secrets.GITHUB_TOKEN}}
+          script: |
+            await github.pulls.merge({
+              owner: context.payload.repository.owner.login,
+              repo: context.payload.repository.name,
+              pull_number: context.payload.pull_request.number,
+              merge_method: 'squash'
+            })