chore: bring in dependabot and its automerge action

.github/dependabot.yml

@@ -0,0 +1,17 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"
+      time: "00:00"
+      timezone: "Etc/UTC"
+    rebase-strategy: 'auto'
+
+  - package-ecosystem: "gomod"
+    directory: /
+    schedule:
+      interval: "daily"
+      time: "00:00"
+      timezone: "Etc/UTC"
+    rebase-strategy: 'auto'

.github/workflows/ci.yml

@@ -29,4 +29,16 @@ jobs:
       - name: "Annotate tests"
         uses: guyarb/golang-test-annotations@v0.5.0
         with:
-          test-results: test.json
+          test-results: test.json
+
+  dependabot-merge:
+    name: "Dependabot auto-merge"
+    runs-on: ubuntu-latest
+    needs: [ "lint", "test" ]
+    permissions:
+      pull-requests: write
+      contents: write
+    steps:
+      - uses: fastify/github-action-merge-dependabot@v3.2.1
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}