fix build

.github/workflows/python_app.yml

@@ -22,8 +22,7 @@ jobs:
         python -m pip install --upgrade pip
         pip install flake8 pytest
         pip install .
-        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
-        if [ -f requirements-dev.txt ]; then pip install -r requirements-dev.txt; fi
+        pip install .[dev]
     - name: Lint with flake8
       run: |
         # stop the build if there are Python syntax errors or undefined names