Update psutil from 5.4.3 to 5.4.4

requirements.txt

@@ -5,7 +5,7 @@ freezegun==0.3.10
 future==0.16.0
 numpy==1.14.2
 pluggy==0.6.0
-psutil==5.4.3
+psutil==5.4.4
 py==1.5.3
 pyglet==1.3.1
 pytest==3.5.0