ci: Stop the build if there are flake8 errors

Author: yammesicka

.github/workflows/python-app.yml

@@ -28,7 +28,7 @@ jobs:
     - name: Lint with flake8
       run: |
         # stop the build if there are Python syntax errors or undefined names
-        flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
+        flake8 . --count --show-source --statistics
         # exit-zero treats all errors as warnings.
         flake8 . --count --exit-zero --max-complexity=10 --statistics
     - name: Test with pytest