Try to fix linter

.github/workflows/linter.yml

@@ -11,7 +11,7 @@ jobs:
       - name: Set up Python 3.8 environment
         uses: actions/setup-python@v1
         with:
-          python-version: 3.8
+          python-version: 3.9
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip