Update pytest from 3.3.2 to 3.4.0

requirements.txt

@@ -8,7 +8,7 @@ pluggy==0.6.0
 psutil==5.4.3
 py==1.5.2
 pyglet==1.3.1
-pytest==3.3.2
+pytest==3.4.0
 python-dateutil==2.6.1
 PyYAML==3.12
 redis==2.10.6