Also update pyyaml in test requirements.
Also update pyyaml in test requirements.

Plexxi/st2,StackStorm/st2,nzlosh/st2,StackStorm/st2,Plexxi/st2,nzlosh/st2,StackStorm/st2,nzlosh/st2,StackStorm/st2,Plexxi/st2,Plexxi/st2,nzlosh/st2