WASHINGTON (Reuters) -U.S. Representative Fred Upton on Tuesday said he will retire from Congress, marking the latest political exit by a Republican lawmaker who voted to impeach then-President Donald Trump. “Even the best stories (have) a last chapter. This is it for me,” the Michigan Republican said in a statement delivered from the U.S. House of Representatives floor. “I’ve signed over a million letters, cast more votes while in the chamber here and accomplished what I set out to do with more unfinished work still yet to come,” added Upton, whose current term ends this year. Upton, 68, was …