Update test.yml

.github/workflows/test.yml

@@ -22,7 +22,8 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install -r requirements.txt
+          pip install flake8 
+          if [ -f requirements.txt ]; then pip install -r requirements.txt;
       - name: Test with Pytest
         run: |
           pip install pytest pytest-cov