chore: Add Dependabot automerge

Author: sapegin

.github/workflows/dependabot.yml

@@ -0,0 +1,22 @@
+name: Dependabot Automerge
+'on': pull_request
+jobs:
+  worker:
+    runs-on: ubuntu-latest
+    if: 'github.actor == "dependabot[bot]"'
+    steps:
+      - uses: actions/github-script@v3
+        with:
+          script: |-
+            github.pulls.createReview({
+              owner: context.payload.repository.owner.login,
+              repo: context.payload.repository.name,
+              pull_number: context.payload.pull_request.number,
+              event: 'APPROVE'
+            })
+            github.pulls.merge({
+              owner: context.payload.repository.owner.login,
+              repo: context.payload.repository.name,
+              pull_number: context.payload.pull_request.number,
+              merge_method: 'squash'
+            })