WASHINGTON — The Supreme Court gave a former UPS driver another chance to prove her claim of discrimination after the company did not offer her lighter duty when she was pregnant. The justices on Wednesday sided 6-3 with former driver Peggy Young in throwing out lower court rulings that rejected her lawsuit. The case concerned employers’ responsibilities under the 37-year-old Pregnancy Discrimination Act. Atlanta-based UPS Inc. maintained that it obeyed the law because it provided light-work duty only …