[CHORE] add daftrunner env to install and test step (#3279)

Co-authored-by: Colin Ho <[email protected]>

.github/workflows/python-publish.yml

@@ -95,6 +95,8 @@ jobs:
         uv pip install -r requirements-dev.txt dist/${{ env.PACKAGE_NAME }}-*x86_64*.whl --force-reinstall
         rm -rf daft
         pytest -v
+      env:
+        DAFT_RUNNER: py
     # Disable until we figure out why are we getting FileNotFoundError: [WinError 3] Failed to open local file
     # - name: Install and test built wheel - Windows x86_64
     #   if: ${{ (matrix.os == 'windows') && (matrix.compile_arch == 'x86_64')  }}