By Jan Wolfe WASHINGTON (Reuters) – An Oath Keepers member on Friday admitted to engaging in seditious conspiracy during the Jan. 6, 2021, attack on the U.S. Capitol and agreed to cooperate with investigators, handing a win to prosecutors as they prepare for a likely trial against the far-right group’s founder. Brian Ulrich, 44, of Georgia pleaded guilty on Friday during a court hearing in federal court in the District of Columbia. Ulrich was one of 11 Oath Keepers members charged with seditious conspiracy in an indictment unsealed in January. The defendants in that case include Stewart Rhodes…