Merge pull request #284 from fantix/pyup-update-pytest-asyncio-0.8.0-to-0.9.0

Update pytest-asyncio to 0.9.0

Author: wwwjfy

requirements_dev.txt

@@ -16,7 +16,7 @@ coverage==4.5.1
 flake8==3.5.0
 pytest==3.6.3
 pytest-runner==4.2
-pytest-asyncio==0.8.0
+pytest-asyncio==0.9.0
 pytest-tornado==0.5.0
 pytest-mock==1.10.0
 pytest-cov==2.5.1