Update psutil from 5.4.0 to 5.4.1

requirements.txt

 freezegun==0.3.9
 packaging==16.8
 numpy==1.13.3
-psutil==5.4.0
+psutil==5.4.1
 py==1.4.34
 pyglet==1.2.4
 pyparsing==2.2.0