ci: add Dependabot auto-merge workflow

Signed-off-by: Marvin Froeder <[email protected]>

Author: velo

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

@@ -0,0 +1,31 @@
+name: Dependabot auto-merge
+on:
+  pull_request:
+    branches:
+      - master
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  dependabot:
+    runs-on: ubuntu-latest
+    if: github.event.pull_request.user.login == 'dependabot[bot]' && github.repository == 'OpenFeign/feign'
+    steps:
+      - name: Dependabot metadata
+        id: metadata
+        uses: dependabot/[email protected]
+        with:
+          github-token: "${{ secrets.GITHUB_TOKEN }}"
+
+      - name: Auto-approve Dependabot PRs
+        uses: hmarr/auto-approve-action@v3
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Enable auto-merge for Dependabot PRs
+        run: gh pr merge --auto --merge "$PR_URL"
+        env:
+          PR_URL: ${{github.event.pull_request.html_url}}
+          GH_TOKEN: ${{secrets.GITHUB_TOKEN}}