Update pytest-asyncio from 0.9.0 to 0.10.0 (#419)

Author: pyup-bot

requirements_dev.txt

@@ -17,7 +17,7 @@ flake8==3.5.0  # pyup: update minor
 tox==3.6.0  # pyup: update minor
 pytest==4.0.0  # pyup: update minor
 pytest-runner==4.2  # pyup: update minor
-pytest-asyncio==0.9.0  # pyup: update minor
+pytest-asyncio==0.10.0  # pyup: update minor
 pytest-tornado5==2.0.0  # pyup: update minor
 pytest-mock==1.10.0  # pyup: update minor
 pytest-cov==2.6.0  # pyup: update minor