feat(ci): integrate mergify and GH action to update flake lock

.github/workflows/update-flake-lock.yml

@@ -0,0 +1,23 @@
+name: Update Flake
+on:
+  repository_dispatch:
+  workflow_dispatch:
+  schedule:
+    - cron: '30 0 * * *'
+permissions:
+  pull-requests: write
+  contents: write
+jobs:
+  createPullRequest:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Nix
+        uses: cachix/install-nix-action@v30
+        with:
+          github_access_token: ${{ secrets.GITHUB_TOKEN }}
+      - name: Update flake.lock
+        uses: DeterminateSystems/update-flake-lock@v24
+        with:
+          pr-labels: |
+            merge-queue

.mergify.yml

@@ -0,0 +1,13 @@
+queue_rules:
+    - name: default
+      merge_conditions:
+          - check-success=buildbot/nix-build
+      merge_method: rebase
+
+pull_request_rules:
+    - name: Queue
+      conditions:
+          - base=main
+          - label~=merge-queue|dependencies
+      actions:
+          queue: