Update pythonpackage.yml

.github/workflows/pythonpackage.yml

@@ -19,7 +19,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install -r requirements.txt
+        pip install -r requirements_dev.txt
     - name: Lint with flake8
       run: |
         pip install flake8