The lastest twist in the Bridges of Madison County saga? Director Bruce Beresford is now considering European actresses to costar with Clint Eastwood in the film of the hugely popular novel. That's bad news to the legion of Hollywood actresses Susan Sarandon, Anjelica Huston, and Cher among them who were said to be interested in playing the farmer's wife who has a four-day affair with a photographer. News that Cher may no longer be in the running has heartened residents of Winterset, Iowa, where the movie begins shooting in September. ''I can't quite see Cher walking down one of our dusty rock roads,'' says Sherry Ellis of Madison County's chamber of commerce. ''We're hoping they cast an unknown Iowan.'' Either way, filming will help the local economy: The producers, Steven Spielberg's Amblin Entertainment, have agreed to hire between 500 and 1,000 locals to work on the film.