After 18 years, the publicity office of Keith Sherman & Associates will no longer represent the Tony Awards.“We’ve had a longer run than ‘Cats,’ ” Sherman said. “We’ve enjoyed amazing longevity and served as a line of continuity through CBS, several administrations of the league and the wing as well as many managing producers and television producers.” The Tonys are presented by the American Theater Wing and the League of American Theaters and Producers. According to the wing’s exec director, Howard Sherman, Tony Awards Prods. will announce a single press rep in four to six weeks. Rubinstein Associates has press-repped the awards with Sherman for three years.