Holdings of SPDR Gold Trust GLD, the world's largest gold-backed exchange-traded fund, fell 0.3% on Monday. By Brijesh Patel June 22 (Reuters) - Gold prices edged higher on Tuesday, as a slight retreat in the dollar offered support to the safe-haven metal, ahead of U.S. Federal Reserve Chairman Jerome Powell's testimony to Congress later in the day. The U.S. economy continues to show "sustained improvement" from the impact of the COVID-19 pandemic and ongoing job market gains, but inflation has "increased notably in recent months," he said in his prepared remarks.