Automatic flake update

.github/workflows/update-flake.yml

@@ -0,0 +1,19 @@
+name: Update Flake
+
+on:
+  schedule:
+    - cron: '0 8 * * *'
+  workflow_dispatch:
+
+jobs:
+  update-flake:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - uses: cachix/install-nix-action@v16
+      with:
+        nix_path: nixpkgs=channel:nixpkgs-unstable
+    - run: nix flake update --recreate-lock-file
+    - uses: stefanzweifel/git-auto-commit-action@v4
+      with:
+        commit_message: "[automation] Update flake"