RHCLOUD-31618 Set up dependabot to automatically update container bas…

…e images

https://issues.redhat.com/browse/RHCLOUD-31618

.github/dependabot.yml

@@ -0,0 +1,11 @@
+version: 2
+updates:
+  - package-ecosystem: "docker"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    groups:
+      base-image:
+        dependency-type: "production"
+    commit-message:
+      prefix: "[base image] "

.github/workflows/dependabot.yml

@@ -0,0 +1,27 @@
+name: Dependabot base-image 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@v2
+        with:
+          github-token: "${{ secrets.GITHUB_TOKEN }}"
+
+      - name: Print metadata
+        run: echo "${{ toJSON(steps.metadata.outputs) }}"
+
+      - name: Enable auto-merge for Dependabot base image PRs
+        if: steps.metadata.outputs.package-ecosystem == 'docker' && 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}}