Manchester United star Kobbie Mainoo has sent a heartfelt message to Gareth Southgate after the former England manager stepped down as head coach of the Three Lions. Gareth Southgate took charge of the England national team in 2016 and succeeded former Three Lions boss Sam Allardyce on a permanent basis. The 53-year-old former England boss led the Three Lions to the final of the 2018 World Cup in Russia before reaching the final of Euro 2020. Despite falling short to Italy in the final of Euro 2020, Southgate remained in charge of England and went on to reach the quarter-finals of the 2022 Wor…