WASHINGTON (Reuters) -A U.S. federal appeals court on Friday upheld the conviction of Steve Bannon, a former top adviser to former President Donald Trump, for defying a subpoena from the congressional panel that investigated the Jan. 6, 2021 attack on the U.S. Capitol. The ruling brings Bannon a step closer to serving a four-month prison sentence for contempt of Congress, but he can still mount additional appeals. Bannon was convicted in 2022 of two misdemeanor counts of contempt of Congress for refusing to turn over documents or testify to the House of Representatives committee that investigated the Capitol riot.