DETROIT — U.S. Rep. John Conyers, D-Detroit, will announce Tuesday that he will not seek another term, but is not resigning, according to a relative who plans to run for his congressional seat. State Sen. Ian Conyers, a great nephew of Conyers, disclosed to the New York Times what he said are the veteran congressman’s plans prior to a scheduled announcement Tuesday morning on a Detroit radio station. “He is not resigning.