Update pytest-tornado from 0.4.5 to 0.5.0

requirements_dev.txt

@@ -17,7 +17,7 @@ aiocontextvars==0.1.2
 sanic==0.7.0
 aiohttp==3.1.3
 tornado==4.5.3
-pytest-tornado==0.4.5
+pytest-tornado==0.5.0
 Pygments==2.2.0
 sphinxcontrib-asyncio==0.2.0
 pytest-mock==1.9.0