By Jarrett Renshaw and David Morgan PHILADELPHIA (Reuters) -Pennsylvania’s hotly contested U.S. Senate Republican primary between TV personality Dr. Mehmet Oz and former hedge fund executive David McCormick was still undecided on Wednesday and could drag on into next week, with a possible recount looming. Oz, whose candidacy was propelled by a late endorsement from former President Donald Trump, led McCormick by just over 500 ballots cast on Tuesday out of nearly 1.3 million counted, while conservative political commentator Kathy Barnette trailed at a distant third, according to Edison Researc…