A state appeals court on Monday rejected a township assessor’s attempt to end a lawsuit filed against him by individuals he claimed were part of a “tax cheating posse.”Stickney Township Assessor Jay Grider accused three current and former Burbank and Cook County officials of engaging in a property tax scheme for years. Those officials turned and sued him over the accusations.The 1st District Appellate Court affirmed Cook County Associate Judge Daniel T. Gillespie’s decision to deny summary judgment …