workflows: update cargo as well (#32)

update both the nix flake and cargo packages

.github/workflows/update.yml

@@ -1,21 +1,31 @@
-name: update-flake-lock
+name: update dependencies
 on:
   workflow_dispatch: # allows manual triggering
   schedule:
     - cron: '0 4 * * *' # at 04:00 every day
 
 jobs:
-  lockfile:
+  cargo:
     runs-on: self-hosted
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
+      - run: nix shell nixpkgs#cargo --command cargo update
+
+  flake:
+    runs-on: self-hosted
+    needs: cargo
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - run: nix flake update
       - name: Check flake
         uses: DeterminateSystems/flake-checker-action@main
+      - run: nix build
       - name: Update Nix Flake Lock
         uses: DeterminateSystems/update-flake-lock@main
         with:
           pr-title: "flake: update flake.lock"
-          pr-reviewers: itepastra
-      - run: nix build
-      - run: nix flake check
+          pr-labels: |
+            dependencies
+            automated