By David Shepardson WASHINGTON (Reuters) -The U.S. Senate on Thursday confirmed by voice vote President Joe Biden’s nominee to serve as the top auto safety regulator, the first to win approval since January 2017 and as U.S. traffic deaths have risen to the highest level in 16 years. Steven Cliff has been serving as deputy administrator of the National Highway Traffic Safety Administration (NHTSA) since February 2021 and was nominated by Biden for the top job in October. His approval by the Senate comes amid soaring U.S. traffic deaths and several ongoing investigations into safety issues at Te…