Update pytest-cov from 2.4.0 to 2.5.0

requirements.txt

@@ -4,7 +4,7 @@ pytest==3.0.7
 pytest-aiohttp==0.1.3
 pytest-asyncio==0.5.0
 pytest-catchlog==1.2.2
-pytest-cov==2.4.0
+pytest-cov==2.5.0
 pytest-flakes==1.0.1
 pytest-mock==1.6.0
 yarl==0.10.2