The White House said Tuesday that nothing has changed since President Joe Biden’s physician said he was “fit for duty” in February and that it was time to “turn the page” on questions about his mental fitness. The assertions came a day after a sixth Democratic House member publicly called on Biden to drop his reelection bid and top Democratic strategist James Carville said it was “only a matter of time” before that happened. During an afternoon news conference, White House press secretary Karine Jean-Pierre was asked whether presidential physician Kevin O’Connor’s Feb. 28 assessment that Biden…