Credit: Travel + Leisure / Jessica Juliao I can’t travel abroad without an underseat bag. It’s the place where I stash my laptop, Kindle, passport, and other things I need to access quickly for my flight. Now, thanks to new legislation, finding the perfect personal item bag for your European flight is easier than ever. The European Union (EU) has voted to prohibit airlines from charging passengers for their underseat bags and carry-on suitcases. Under the new law, fliers' personal item bags can't exceed 15.7 inches by 11.8 inches by 5.9 inches, while suitcases must be under 39.3 inches and weigh no more than 15 pounds. Luckily, Amazon is filled with quality underseat bags, many of which are on sale right now. We even found discounts on Travel + Leisure editor-trusted brands, like Samsonite and Travelpro. These deals are all selling out quickly, though, so add these bags to your cart before it’s too late.…