fix tests for pixi
fix tests for pixi

Luwdo/PhysicsJS,Nayar/PhysicsJS,Nayar/PhysicsJS,Rawneed/PhysicsJS,rohit765/PhysicsJS,eric-seekas/PhysicsJS,wellcaffeinated/PhysicsJS,griever989/PhysicsJS,haithemaraissia/PhysicsJS,rohit765/PhysicsJS,Rawneed/PhysicsJS,mcanthony/PhysicsJS,haithemaraissia/PhysicsJS,jpellerin/PhysicsJS,eric-seekas/PhysicsJS,pietro909/PhysicsJS,pietro909/PhysicsJS,VANITAX/PhysicsJS,VANITAX/PhysicsJS,Luwdo/PhysicsJS,mcanthony/PhysicsJS,wellcaffeinated/PhysicsJS,jpellerin/PhysicsJS,griever989/PhysicsJS