By Nathan Layne and Jacqueline Thomsen MARIETTA, Ga., (Reuters) – With just hours left before U.S midterm voters head to the polls on Tuesday, courts are hearing a handful of last-minute lawsuits that could affect election rules and the counting of ballots in battleground states. U.S. Senate candidate John Fetterman and other Democrats sued in Pennsylvania federal court on Monday to force officials to include undated mail-in ballots in the state’s vote count, following a similar lawsuit on behalf of voting rights groups by the American Civil Liberties Union in Pennsylvania on Friday. The lawsu…