ci: add nix flake auto updater

.github/CODEOWNERS

@@ -2,6 +2,11 @@
 /.github                                                 @osrd-project/devops
 /.github/CODEOWNERS                                      @flomonster @bloussou @nicolaswurtz
 
+# --- NIX ---
+/nix                                                     @osrd-project/devops
+/flake.lock                                              @osrd-project/devops
+*.nix                                                    @osrd-project/devops
+
 # --- FRONT ---
 /front                                                   @osrd-project/front-maintainers
 /front/src/common/api/osrdEditoastApi.ts

.github/workflows/update_nix_flake.yml

@@ -0,0 +1,22 @@
+name: update_nix_flake
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: '0 0 1 * *'
+
+jobs:
+  lockfile:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@main
+      - name: Update flake.lock
+        uses: DeterminateSystems/update-flake-lock@main
+        with:
+          commit-msg: "ci: update flake.lock"
+          pr-title: "ci: update flake.lock"
+          pr-labels: |
+            dependencies