use python 3.8 in ci

Author: r2dev2

.github/workflows/pypi-publish.yml

@@ -12,7 +12,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v1
       with:
-        python-version: '3.6'
+        python-version: '3.8'
     - name : Print GitHub context
       env: 
         GITHUB_CONTEXT: ${{ toJson(github) }}