fix the github action

.github/workflows/python-app.yml

@@ -32,7 +32,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install flake8 pytest
+        pip install flake8 pytest cryptography
         pip install -r requirements.txt
     - name: Lint with flake8
       run: |