call pytest as a module

.github/workflows/python-app.yml

@@ -31,9 +31,9 @@ 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 --select=E9,F63,F7,F82 --show-source --statistics --extend-exclude=app/tests/*.py system_tests/*.py
         # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
         flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
     - name: Test with pytest
       run: |
-        pytest
+        python -m pytest app