💚 Dependabot の自動マージワークフローを追加

.github/workflows/dependabot-auto-merge.yml

@@ -0,0 +1,41 @@
+name: "Dependabot auto-merge"
+
+on:
+  pull_request: ~
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  dependabot:
+    runs-on: ubuntu-22.04
+    if: github.actor == 'dependabot[bot]'
+    steps:
+      # https://github.com/marketplace/actions/create-github-app-token
+      - name: Create GitHub App Token
+        uses: actions/create-github-app-token@v1.6.2
+        id: app-token
+        with:
+          app-id: ${{ vars.BOT_APP_ID }}
+          private-key: ${{ secrets.BOT_PRIVATE_KEY }}
+
+      # https://github.com/marketplace/actions/fetch-metadata-from-dependabot-prs
+      - name: Dependabot metadata
+        id: metadata
+        uses: dependabot/fetch-metadata@v1.6.0
+        with:
+          github-token: "${{ steps.app-token.outputs.token }}"
+
+      - name: Enable auto-merge for Dependabot PRs
+        if: |
+          steps.metadata.outputs.update-type == 'version-update:semver-patch' ||
+          steps.metadata.outputs.update-type == 'version-update:semver-minor'
+        run: |
+          gh pr review --approve "$PR_URL"
+          gh pr edit "$PR_URL" -t "(auto merged) $PR_TITLE"
+          gh pr merge --auto --merge "$PR_URL"
+        env:
+          PR_URL: ${{ github.event.pull_request.html_url }}
+          PR_TITLE: ${{ github.event.pull_request.title }}
+          GH_TOKEN: ${{ steps.app-token.outputs.token }}