By Jonathan Allen (Reuters) -A woman and two children drowned in the Rio Grande as they tried to the enter the U.S. from Mexico on Friday night after Texas military officers prevented federal border officials from aiding them, U.S. border officials and a member of Congress said. The deaths come as a dispute over immigration intensifies between Texas Governor Greg Abbott, a Republican, and the administration of U.S. President Joe Biden, a Democrat, with a record number of migrants having illegally crossed the border since Biden took office in 2021. Under Abbott, Texas has increasingly sought to…