Update pytest from 3.4.2 to 3.5.0

requirements.txt

 psutil==5.4.3
 py==1.5.3
 pyglet==1.3.1
-pytest==3.4.2
+pytest==3.5.0
 python-dateutil==2.7.0
 PyYAML==3.12
 redis==2.10.6