Celtic have had a whirlwind transfer window this summer, and things are only expected to pick up in the coming days. Having sold Matt O’Riley for a Scottish Premiership record £30m to Brighton & Hove Albion, there could be a flurry of activity from the Hoops, with Celtic already linked with a move for Sheffield United defender Auston Trusty. With Celtic also eyeing Arne Engels as a replacement for O’Riley, the reigning Scottish champions could be in for a chaotic final moments in the summer transfer window having already made some top moves in the market. And the Hoops have now told one key pl…