CI: Upload distributions for manual checks

Author: effigies

.github/workflows/pythonpackage.yml

@@ -68,6 +68,10 @@ jobs:
       run: python setup.py sdist bdist_wheel
     - name: Check distributions
       run: twine check dist/*
+    - uses: actions/upload-artifact@v2
+      with:
+        name: distributions
+        path: dist/
     - name: Upload to PyPI (on tags)
       if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags')
       uses: pypa/gh-action-pypi-publish@master