Mint Butterfield, the child of divorced tech billionaires Caterina Fake and Stuart Butterfield, was found safe, six days after they were initially reported missing. Fake and Butterfield co-founded Flickr before their divorce. Butterfield is also the founder and former CEO of Slack, while Fake previously served as the chairwoman of Etsy. Mint, 16, was last seen at a bus stop 30 miles northeast of San Francisco on April 21. The teenager lives with their mother and attends boarding school in the Napa area. Mint’s parents and stepfather, Jyri Engestrom, released a joint statement Sunday thanking t…