“We don’t do anything with dignity, okay?” Rebel Wilson’s “Fat Amy” (her ball cap reads “Make America Eat Again”) says in this first trailer for Pitch Perfect 3, and fans wouldn’t expect otherwise. Having graduated from college and finding the non-singing world a depressing place – service jobs and bull-tending apparently not being all their cracked up to be – the a cappella Bellas reunite for a USO competition in Europe, where they’ll once again sing off against snooty…