By Caroline Gaspich Stranger Things fans are filled with bittersweet excitement as the original cast reunites once again to officially begin production for the last and final season of the series. In celebration of the milestone, Netflix teased season 5 with a never-before-seen snap of the reunited cast as they started filming this week. Fans have been eagerly awaiting the new season as viewers were left on a cliffhanger at the end of season four when Murray and Hopper heroically defeated a gang of deadly demogorgons in the Upside Down universe giving the gang of friends back in a chance to sa…