Whether you’ve gotten your second vaccine shot or you’re just feeling more cooped up than ever, Scott Keyes has advice for those who want to travel in 2021: Buy your tickets now. “You still haven’t seen the full amount of pent-up travel demand get released yet,” said the founder of deal-tracking site Scott’s Cheap Flights. “There’s still a ton of room to grow, and it’s just starting to get released. There are still a lot of cheap summer flights available right now, but if you wait to book your flight until May, and you’re hoping to travel over the summer, your chances of getting a cheap summer flight at that…