Must build artifact before uploading

Author: jburgy

.github/workflows/pythonpackage.yml

@@ -29,6 +29,7 @@ jobs:
       uses: codecov/test-results-action@v1
       with:
         token: ${{ secrets.CODECOV_TOKEN }}
+    - run: uv build
     - uses: actions/upload-artifact@v4
       with:
         name: python-package-distributions