github ci: report any flake8 code as failure.

.github/workflows/ci.yml

@@ -7,7 +7,7 @@ on:
     branches: [ master ]
 
 jobs:
-  build:
+  check:
 
     runs-on: ubuntu-latest
     strategy:
@@ -27,10 +27,7 @@ jobs:
         if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
     - 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
-        # exit-zero treats all errors as warnings
-        flake8 . --count --exit-zero --statistics
+        flake8 . --show-source
     - name: Run unit tests
       run: |
         python -m unittest -v