Check outdated packages

.github/workflows/ci.yaml

@@ -2,6 +2,8 @@ name: CI
 on:
   pull_request:
   push:
+  schedule:
+    - cron: '23 1 * * *' # *-*-* 01:23:00 UTC
 
 permissions:
   contents: read
@@ -104,3 +106,16 @@ jobs:
           github_access_token: ${{ secrets.GITHUB_TOKEN }}
       - name: Nix build
         run: nix-build --show-trace
+
+  outdated:
+    name: Outdated
+    runs-on: ubuntu-latest
+    if: github.event_name != 'pull_request'
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Install cargo-outdated
+        uses: dtolnay/install@cargo-outdated
+      - run: |
+          rm Cargo.lock # Ignore trivially updatable compatible versions.
+          cargo outdated --workspace --exit-code 1