ci: Install flake8, isort

Author: jpmckinney

.github/workflows/lint.yml

@@ -9,5 +9,6 @@ jobs:
       - uses: actions/setup-python@v5
         with:
           python-version: '3.10'
+      - run: pip install --upgrade flake8 isort
       - run: flake8 .
       - run: isort .