WASHINGTON (Reuters) - Asian stocks struggled to extend the week's rally on Wednesday and gold and bonds firmed as a sceptical press report dented some hopes for a COVID-19 vaccine and concerns about bumps in the global recovery from the pandemic returned.MSCI's broadest index of Asia-Pacific shares outside Japan was flat. The risk-sensitive Australian dollar retreated from an overnight two-month high and safe-haven demand drove U.S. Treasury yields back under 0.7%.[FRX/][US/]The moves follow a..