fix required Grunt version mentioned in README

Author: cvrebert

README.md

@@ -7,7 +7,7 @@
 
 ## Getting Started
 
-This plugin requires Grunt `~0.4.2`.
+This plugin requires Grunt `~0.4.3`.
 
 If you haven't used [Grunt](http://gruntjs.com/) before, be sure to check out the [Getting Started](http://gruntjs.com/getting-started) guide, as it explains how to create a [Gruntfile](http://gruntjs.com/sample-gruntfile) as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command: