Sen. JD Vance (R-Ohio) likely didn’t win over many firefighters to the Republican ticket, judging by a speech he delivered on Thursday. During a meeting of the International Association of Fire Fighters (IAFF) — which is part of the hugely influential AFL-CIO — Vance addressed the Boston, Massachusetts crowd of union firefighters as part of former President Donald Trump’s efforts to make inroads with union workers. But Vance’s speech was interrupted by loud boos after he tried to tout the GOP ticket’s “pro-worker” bona fides. “President Trump and I are proud to be the most pro-worker Republica…