By Caroline Gaspich Meghan Markle and Prince Harry were spotted reuniting with their longtime friend, athlete Serena Williams at a recent polo match, as they gear up for their latest Netflix project. This week, the Sussexes attended the Royal Salute Polo Challenge at the Grand Champions Polo Club in Wellington, Florida, where they caught up with one of the greatest tennis players of all time. During the polo match, Meghan and her close pal Serena looked in high spirits as they chatted and laughed with Prince Harry, checked out the polo horses, rode around in a golf cart, and cheered on the pla…