Update pythonapp.yml

.github/workflows/pythonapp.yml

@@ -23,7 +23,8 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install -r requirements.txt
+        pip install poetry
+        poetry install
     - name: Lint with flake8
       run: |
         pip install flake8