ci(dependabot): enable auto-merge for upgrades

.github/workflows/dependabot-automerge.yaml

@@ -0,0 +1,29 @@
+name: Dependabot auto-merge
+
+on:
+  pull_request:
+    branches:
+      - 'main'
+
+permissions:
+  contents: read # for actions/checkout to fetch code
+
+jobs:
+  dependabot:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+    if: github.event.pull_request.user.login == 'dependabot[bot]' && github.repository == 'weaveworks/weave-gitops'
+    steps:
+      - name: Dependabot metadata
+        id: metadata
+        uses: dependabot/fetch-metadata@dbb049abf0d677abbd7f7eee0375145b417fdd34 # v2.2.0
+        with:
+          github-token: "${{ secrets.GITHUB_TOKEN }}"
+      - name: Enable auto-merge for Dependabot PRs
+        if: steps.metadata.outputs.update-type == 'version-update:semver-minor'
+        env:
+          PR_URL: ${{github.event.pull_request.html_url}}
+          GH_TOKEN: ${{secrets.GITHUB_TOKEN}}
+        run: gh pr merge --auto --rebase "$PR_URL"