Add cache clearing step before installing dependencies in lint workflow

.github/workflows/lint.yml

@@ -25,7 +25,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v2
         with:
-          python-version: '3.8'
+          python-version: '3.9'
       - name: Clear Cache
         run: sudo rm -rf ~/.cache/pip
       - name: Install Dependencies