Add nix-flake lock update github workflow

Author: HalidOdat

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

@@ -0,0 +1,34 @@
+# https://github.com/dependabot/dependabot-core/issues/7340
+
+name: Update nix-flake lock
+on:
+  workflow_dispatch: # allows manual triggering
+  schedule:
+    - cron: "0 0 * * 0" # runs weekly on Sunday at 00:00
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  lockfile:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Install nix
+        uses: nixbuild/nix-quick-install-action@v30
+
+      - name: Update flake.lock
+        uses: DeterminateSystems/update-flake-lock@v24
+        with:
+          token: ${{ secrets.GH_TOKEN_NIX_FLAKE_UPDATE }}
+          commit-msg: Update flake.lock
+          branch: update/nix-flake-lock-action
+          pr-title: Update flake.lock
+          pr-labels: |
+            A-nix
+            C-dependency
+          pr-body: |
+            {{ env.GIT_COMMIT_MESSAGE }}