Update python-publish.yml

.github/workflows/python-publish.yml

@@ -24,10 +24,10 @@ jobs:
         uses: actions/checkout@v2
         with:
             submodules: true
-      - name: Set up Python 3.8
+      - name: Set up Python 3.9
         uses: actions/setup-python@v2
         with:
-          python-version: 3.8
+          python-version: 3.9
       - name: Build sdist
         shell: bash
         run: |