Ensure we actually checkout the project

Author: jb3

.github/workflows/lint-test.yaml

@@ -8,6 +8,9 @@ jobs:
     name: Run linting & tests
     runs-on: ubuntu-latest
     steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
       - name: Install uv
         uses: astral-sh/setup-uv@v6
         with: