PHILADELPHIA — Former President Donald Trump is headed to Philadelphia on Saturday to speak at Sneakercon, a large-scale gathering for sneaker enthusiasts taking place at the Pennsylvania Convention Center. Trump announced he would speak at the convention on his social media platform Truth Social on Friday, and a spokesperson for the Convention Center confirmed his appearance. Trump, the front-runner for the Republican presidential nomination, is slated to speak at 3 p.m. before traveling to Michigan for a planned evening rally there. Sneakercon organizers did not respond to requests for more …