auto update flake lock

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

@@ -0,0 +1,18 @@
+name: update-flake-lock
+on:
+  workflow_dispatch: # allows manual triggering
+  schedule:
+    - cron: '0 0 * * 1,4' # Run twice a week
+
+jobs:
+  lockfile:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+      - name: Install Nix
+        uses: cachix/install-nix-action@v18
+      - name: Update flake.lock
+        uses: DeterminateSystems/update-flake-lock@v14
+        with:
+          token: ${{ secrets.GH_TOKEN_FOR_UPDATES }}