fix: publish failure

Author: Hongbin Huang

.github/workflows/publish.yml

@@ -13,7 +13,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: 3.6
+          python-version: 3.9
       - name: Install Flit
         run: pip install flit
       - name: Install Dependencies