By Zach Koons Pittsburgh Steelers quarterback Ben Roethlisberger officially announced his retirement from the NFL in a video posted to social media on Thursday morning. The post confirmed what had been reported for the last few weeks that the 2021 season would be Roethlisberger’s last. The 39-year-old will leave the Steelers as one of the most memorable players in franchise history and a future Hall of Famer. “I don’t know how to put into words what the game of football has meant to me and what a blessing it has been. While I know with confidence that I have given my all to the game, I am over…