feat: add dependabot auto-merge on PRs

There's an issue that will occur if we do not maintain the very tip of the runner execution script, they become deprecated after a month. We need to auto-merge these so clusters consuming this image will not cease to function when inevitably they do deprecate the source image.

.github/workflows/pr.yml

@@ -5,6 +5,10 @@ on:
     branches:
       - main
 
+permissions:
+  contents: write
+  pull-requests: write
+
 jobs:
   create_matrix:
     uses: ./.github/workflows/create_matrix.yml
@@ -48,3 +52,19 @@ jobs:
 
       - name: Check build status
         run: docker run --rm localhost:5000/${{ steps.set_image_name.outputs.image_name }}:latest
+
+  dependabot:
+    runs-on: ubuntu-latest
+    if: github.actor == 'dependabot[bot]'
+    steps:
+      - name: Dependabot metadata
+        id: metadata
+        uses: dependabot/fetch-metadata@v2
+        with:
+          github-token: "${{ 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 }}
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}