John Hartson has sent a message to Joe Hart after the Celtic goalkeeper’s Hampden heroics sent the Parkhead club into the Scottish Cup final yesterday. Hart is set to retire at the end of the season and has, without a doubt, been one of Celtic’s best players under Brendan Rodgers. Yesterday was Hart’s 147th appearance for Celtic since he joined the club from Tottenham under Ange Postecoglou. In that time he has made 61 clean sheets and picked up five trophies. [Transfermarkt] And whilst Hart does have his critics and has made more than his fair share of mistakes, no one can deny that he has be…