Amazon refreshed every model in its Kindle lineup earlier this month, introducing its first-ever colour e-ink screen, faster page-turns, and brighter backlights for late-night reading. It’s an exciting new lineup, but if the new hardware isn’t enough to entice you already Amazon has an incredible giveaway up its sleeve. For a limited time, anyone who upgrades to a new Kindle model will unlock a three-month Kindle Unlimited subscription at no extra cost. Worth £9.49 per month, Kindle Unlimited offers access to millions of fiction and non-fiction books, audiobooks, and magazines on your Kindle a…