By Ismail Shakil and Mike Stone (Reuters) -President Joe Biden has accepted the resignation of U.S. Customs and Border Protection Commissioner Christopher Magnus, the White House said in a statement on Saturday. The White House statement comes a day after U.S. media reported that Magnus had been asked to resign or was fired in a sign of tensions within Biden’s administration over a record number of migrant crossings at the U.S.-Mexico border. “I am submitting my resignation effective immediately but wish you and your administration the very best going forward. Thank you again for this tremendo…