Re-upgrade to phpunit 5.x. Added note in README to explain dependency on PHP 5.6 for tests.

Author: szainmehdi

README.md

@@ -10,6 +10,8 @@ Cast your Eloquent model attributes to value objects with ease!
 
 This package requires PHP >= 5.4. Using the latest version of PHP is highly recommended. Laravel 4.x and 5.x are supported.
 
+> **Note:** Running tests for this package requires PHP >=5.6.
+
 ### Install
 
 Require this package with composer using the following command:

composer.json

@@ -21,6 +21,6 @@
         "laravel/framework": ">=4.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^4.0"
+        "phpunit/phpunit": "^5.0"
     }
 }