By Olivia Wheeler Britain’s Got Talent viewers were left amazed over the show’s ‘best audition yet’ on Saturday night. During the latest instalment, Abigail, seven, and Afronitaaa, 20, performed an incredible routine to a medley of tracks. Ahead of the performance, Afronitaaa said she decided to mentor Abigail, who is deaf, after seeing her dancing videos online. The duo performed an incredible routine on stage, receiving a standing ovation from the audience and judges for their performance. Simon Cowell said they were one of his “favourite auditions of the year” while Amanda Holden added: “Yo…