Former President Donald Trump may have gotten himself in some hot water Friday afternoon when he played the popular 1997 anthem “My Hero” by the Foo Fighters as he welcomed Robert F. Kennedy to the stage at his Glendale, Arizona, rally. Kennedy’s walk-out to the song — with fireworks igniting behind him and Trump — caught the attention of the band, who delivered a stern response. “Foo Fighters were not asked permission, and if they were, they would not have granted it,” a spokesperson told Billboard. The person added that “appropriate actions are being taken” against Trump’s campaign, and that…