Update pythonpublish.yml

Author: mirceaulinic

.github/workflows/pythonpublish.yml

@@ -13,7 +13,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v1
       with:
-        python-version: '3.x'
+        python-version: '3.6'
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip