An Oura Ring Gen 3 Horizon smart ring.Source: T3/Getty ImagesOura Health Oy, the maker of the popular Oura health and fitness ring, is closing in on a roughly $11 billion valuation after selling about 3 million rings over the past year.The Finnish company is raising $875 million in a new Series E financing round valuing it around $10.9 billion, according to people familiar with the matter. That would double Oura’s $5 billion valuation from its Series D round last November....