Set CI to py39 for now

Author: tuxillo

.github/workflows/lint.yml

@@ -12,7 +12,7 @@ jobs:
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v4
         with:
-          python-version: '3.x'
+          python-version: '3.9'
           cache: 'pip'
       - name: Install dependencies
         run: |