Celtic boss Brendan Rodgers will already be mapping out where to strengthen his squad once the summer transfer window opens for business. Several positions may be bolstered; however, the most certain priority is between the sticks, owing to Joe Hart’s retirement from professional football at the end of this campaign. The former England goalkeeper to date has made 143 appearances for Celtic, keeping 59 clean sheets in the process [Transfermarkt]. Nevertheless, new heroes will arise at Parkhead, and there have already been suggestions from media circles across Europe as to who our new number one…