changing flake8 arguments to make it fail with the legacy code

Author: francescodelduchetto

.github/workflows/ci.yml

@@ -103,7 +103,7 @@ jobs:
         run: |
           pip install flake8
           # E9,F63,F7,F82 flag fatal syntax errors and undefined names
-          flake8 ./backend --count --select=E9,F63,F7,F82 --show-source --statistics
+          flake8 ./backend --count --max-complexity=5 --show-source --statistics
       # just a placeholder for your tests. Implement your actual test commands here, e.g. "pytest ..."
       - name: Run tests with coverage
         run: |