Sets auto merge for PRs opened by dependabot to true. (#293)

Sets auto merge for PRs opened by dependabot to true.
Review is still needed.

.github/workflows/dependabot-approve.yaml

@@ -0,0 +1,24 @@
+# https://docs.github.com/de/code-security/dependabot/working-with-dependabot/automating-dependabot-with-github-actions#enable-auto-merge-on-a-pull-request
+name: Dependabot auto-merge
+on: pull_request
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  dependabot:
+    runs-on: ubuntu-latest
+    if: ${{ github.actor == 'dependabot[bot]' }}
+    steps:
+    - name: Dependabot metadata
+      id: metadata
+      uses: dependabot/fetch-metadata@v1
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}
+    - name: Enable auto-merge for Dependabot PRs
+      if: ${{contains(steps.metadata.outputs.dependency-names, 'my-dependency') && steps.metadata.outputs.update-type == 'version-update:semver-patch'}}
+      run: gh pr merge --auto --merge "$PR_URL"
+      env:
+        PR_URL: ${{github.event.pull_request.html_url}}
+        GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}