Hong Kong’s first voluntary citywide Covid-19 testing scheme will be extended for four days after it continued to detect a few cases on Friday, the Post has learned.Separately, the Department of Health is expected to confirm more than 10 new cases from the community today.Sources familiar with the government’s position said officials would extend the free programme, initially scheduled to last a week, but may not prolong it for seven days in one go, or open all 141 sample collection points.“The…