By Katie Catherall Arsenal manager Mikel Arteta says William Saliba and Gabriel’s natural “chemistry” is one of the keys to their successful partnership. Saliba and Gabriel are regarded by many to be the Premier League’s top centre-back duo, with each playing starring roles as Arsenal look to end their 20-year wait for a league title. The Gunners play host to relegation strugglers Luton Town on Wednesday night, where they will hope to put the pressure on table-toppers Liverpool with a valuable three points, and Arteta was asked in his pre-match press conference when he first thought the pair c…