chore: replace lockfile auto-update with uv lock --check

.github/workflows/test.yml

@@ -21,6 +21,9 @@ jobs:
       - name: Set up Python
         run: uv python install 3.13
 
+      - name: Check lockfile is up to date
+        run: uv lock --check
+
       - name: Install dependencies
         run: uv sync --extra cpu