ci: use --locked flag in uv sync in CI

This makes sure the lock file is up-to-date.

Author: sd2k

.github/workflows/python.yml

@@ -34,7 +34,7 @@ jobs:
           python-version-file: "pyproject.toml"
 
       - name: Install the project
-        run: uv sync --all-extras --all-groups
+        run: uv sync --all-extras --all-groups --locked
 
       - name: Run ruff
         run: uv run ruff check .