A week after Jimmy Buffett died, they released the new hit “Bubbles Up,” aided by former Beatle Paul McCartney calling the song his best — A week after Jimmy Buffett died, his new song “Bubbles Up” was released. Sir Paul McCarney called it “probably the best I’ve heard him sing ever.” Is “Bubble’s Up” Buffett’s best song ever? Will it be as big a hit as his earlier hits? I have no idea, but we…