update test.yml

Author: luolingchun

.github/workflows/test.yml

@@ -28,7 +28,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
-          pip install pytest
+          pip install pytest flake8
           pip install -e .
       - name: Test with pytest
         run: |