Update python package to 3.8

Python 3.10 collection changes cause error in nose test

Author: rlupat

.github/workflows/publish.yml

@@ -13,7 +13,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v2
       with:
-        python-version: '3.x'
+        python-version: '3.8'
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
@@ -30,4 +30,4 @@ jobs:
         TWINE_PASSWORD: ${{ secrets.PYPI_PASSWORD }}
       run: |
         python setup.py sdist bdist_wheel
-        twine upload dist/*
+        twine upload dist/*