By Humeyra Pamuk, Patricia Zengerle and Mike Stone WASHINGTON (Reuters) – U.S. President Joe Biden’s White House sent a letter to members of Congress on Wednesday urging approval of a $20 billion sale of Lockheed Martin F-16 aircraft and modernization kits to Turkey, three sources familiar with the letter told Reuters. Turkey’s parliament ratified Sweden’s NATO membership bid on Tuesday, clearing a major hurdle to expanding the Western military alliance after 20 months of delay. The sources said the letter was sent on Wednesday, and that the administration has not yet formally notified Congres…