Fix pip-install import test by avoiding local source shadow

The import verification runs from the repo root, where the local vplanet/
source directory shadows the installed package. The local source lacks the
compiled C extension (vplanet_core), causing ModuleNotFoundError. Fix by
cd'ing to /tmp before running the import test.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: RoryBarnes

.github/workflows/pip-install.yml

@@ -37,13 +37,13 @@ jobs:
         run: |
           python -m venv venv-sdist
           venv-sdist/bin/python -m pip install dist/vplanet*.tar.gz
-          venv-sdist/bin/python -c "import vplanet; print(vplanet.__version__)"
+          cd /tmp && "$GITHUB_WORKSPACE/venv-sdist/bin/python" -c "import vplanet; print(vplanet.__version__)"
 
       - name: Test the wheel
         run: |
           python -m venv venv-wheel
           venv-wheel/bin/python -m pip install dist/vplanet*.whl
-          venv-wheel/bin/python -c "import vplanet; print(vplanet.__version__)"
+          cd /tmp && "$GITHUB_WORKSPACE/venv-wheel/bin/python" -c "import vplanet; print(vplanet.__version__)"
 
       - uses: actions/upload-artifact@v4
         with: