Merge pull request #43 from wgmv/laravel-mix-4

bumps laravel-mix to 4 and laravel-mix-purgecss to 4.1

Author: michaeldyrynda

src/TailwindCssPreset.php

@@ -27,8 +27,8 @@ public static function installAuth()
     protected static function updatePackageArray(array $packages)
     {
         return array_merge([
-            'laravel-mix' => '^2.1',
-            'laravel-mix-purgecss' => '^2.2',
+            'laravel-mix' => '^4.0.14',
+            'laravel-mix-purgecss' => '^4.1',
             'laravel-mix-tailwind' => '^0.1.0',
         ], Arr::except($packages, [
             'bootstrap',