ci: checkout before downloading wheel artifact (checkout cleans workspace)

Author: cpsievert

.github/workflows/python.yml

@@ -96,13 +96,14 @@ jobs:
     runs-on: ubuntu-latest
     needs: test
     steps:
+      # NOTE: checkout must precede the download — it cleans the workspace.
+      - uses: actions/checkout@v4
+
       - uses: actions/download-artifact@v4
         with:
           name: ggsql-wheel
           path: wheelhouse
 
-      - uses: actions/checkout@v4
-
       - name: Smoke test wheel in a minimal container
         run: |
           WHEEL=$(basename wheelhouse/*.whl)