Update aiopg from 0.14.0 to 0.16.0

Author: pyup-bot

requirements-dev.txt

@@ -3,7 +3,7 @@ aiohttp-security==0.4.0
 aiohttp-session==2.7.0
 aiohttp==3.5.4
 aiomysql==0.0.20
-aiopg==0.14.0
+aiopg==0.16.0
 coverage==4.5.1
 docker==3.3.0
 flake8==3.5.0