By Jamie Spencer Manchester City boss Pep Guardiola has claimed he will retire in a matter of months if his team successfully defends last season’s Premier League, FA Cup and Champions League treble. Guardiola has a contract at the Etihad Stadium until 2025 but surprisingly declared ahead of Wednesday night’s Premier League defeat to Aston Villa that he will walk away completely at the end of this campaign if City have won the treble for a second successive season. “If we win the treble this season, I’ll retire. That’s for sure,” the Spaniard told Prime Video, perhaps serious, perhaps not. “I …