Update py from 1.5.3 to 1.5.4

requirements.txt

 numpy==1.14.5
 pluggy==0.6.0
 psutil==5.4.6
-py==1.5.3
+py==1.5.4
 pyglet==1.3.2
 pytest==3.6.2
 python-dateutil==2.7.3