ci: add auto merge workflow for flake updates

.github/workflows/auto-merge.yml

@@ -0,0 +1,21 @@
+name: Auto Merge Dependency Updates
+
+on:
+  - pull_request_target
+
+jobs:
+  auto-merge-dependency-updates:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+    concurrency:
+      group: "auto-merge:${{ github.head_ref }}"
+      cancel-in-progress: true
+    steps:
+      - uses: Mic92@auto-merge@master
+        with:
+          merge-method: rebase
+          approve: true
+          required-labels: dependencies,auto-merge
+          use-auto-merge: true