Gennady Golovkin said the prospect of a third fight against Saul ‘Canelo’ Alvarez was “interesting” after the Kazakh star homed in on a long-awaited trilogy by beating Japan’s Ryota Murata on Saturday. “GGG” Golovkin, who turned 40 on Friday, stopped Murata in the ninth round to add the Japanese fighter’s WBA middleweight world title to his own IBF belt in a unification bout in Saitama, north of Tokyo. The win moved Golovkin a step closer to a third crack at pound-for-pound king Alvarez, having pushed the Mexican all the way in two previous epic encounters. The all-conquering Alvarez, having l…