Update flake8 version in github action

.github/workflows/linting.yaml

@@ -23,7 +23,7 @@ jobs:
         if: always()
         run: |
           python -m pip install --upgrade pip
-          pip install flake8==3.9.1 pylint==2.13.8
+          pip install flake8==4.0.1 pylint==2.13.8
           #if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
       - name: Run black
         uses: psf/black@stable