By Daniel Orme Eintracht Frankfurt boss Dino Toppmoller has issued a grovelling apology to Donny van de Beek after leaving the Manchester United star out of his European squad. The Dutch midfielder joined the German outfit on loan until the end of the season after a rotten campaign at Old Trafford. Despite the move, Van de Beek’s career has slumped to new lows. It was announced that he wasleft out of Frankfurt’s 25-man squad for the knockout rounds of the Europa Conference League. Head coach Toppmoller has since explained that decision and revealed that he felt compelled to apologise to Van de…