The woman charged with spitting in an NYPD sergeant’s face at a Manhattan protest whined Thursday to The Post that she did so because cops were “attacking people.” Reached by phone, Devina Singh said she’d just been released from court following her arrest during a tumultuous night of anti-cop demonstrations by left-wing radicals chanting, “Burn the precinct to the ground!” Asked why she spat in the sergeant’s face, she claimed: “After they hit us with their bikes repeatedly … and started