docs: Update download count in README.md (#539)

README.md

@@ -34,7 +34,7 @@ all with sensible defaults
 
 - Has been used to create demos for several W3C specifications
 - Has been used by browsers to test their CSS Color 4/5 implementations
-- Over [2 million total npm downloads](https://limonte.dev/total-npm-downloads/?package=colorjs.io)!
+- Over [3 million total npm downloads](https://limonte.dev/total-npm-downloads/?package=colorjs.io)!
 - Used by several [high impact projects](https://www.npmjs.com/browse/depended/colorjs.io), including [Sass](https://sass-lang.com/), [Open Props](https://open-props.style/), [axe](https://www.deque.com/axe/) accessibility testing engine, and [OddContrast](https://www.oddcontrast.com/) and [CSS HD Gradients](https://gradient.style/) color tools
 - Parts of Color.js’s API are used as a testing ground for the design of a [native `Color` object for the Web platform](https://github.com/wicg/color-api).