Require $config to implement the ConfigContract
Require $config to implement the ConfigContract

This fixes issues with setups that don't use the Laravel provided `Illuminate\Config\Repository` class for their config repository but are still compatible with the rest of the Laravel ecosystem by implementing the `Illuminate\Contracts\Config\Repository` in their Config Repository class.

Specifically in my case, this adds support for using this package within [OctoberCMS](https://github.com/octobercms/october) (most popular Laravel-based CMS) - as October uses `October\Rain\Config\Repository` which is not an instanceof `Illuminate\Config\Repository` but still implements the required `Illuminate\Contracts\Config\Repository` contract that the default Laravel config repository class does as well.
mewebstudio/Purifier