Arsenal face a race against time if they are to add a new attacker to their ranks before the summer transfer window closes. With the transfer deadline coming at 11pm on Friday, clubs all around the Premier League are now scrambling to get their last bits of business done. Arsenal have added two new faces to their first team squad so far this summer. First, Riccardo Calafiori arrived from Bologna to swell Mikel Arteta’s defensive options. Then, yesterday, Arsenal announced the signing of Mikel Merino, bringing to an end the extended transfer saga that has surrounded the Spanish midfielder. Howe…