Update ApiBase.php
Update ApiBase.php

In API DOC : https://docs.mangopay.com/guide/authentification

POST: https://api.mangopay.com/v2.01/oauth/token/ (change the subdomain to api.sandbox... to use the sandbox environment)

Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW

Content-Type: application/x-www-form-urlencoded

Form data: grant_type=client_credentials
Mangopay/mangopay2-php-sdk,Mangopay/mangopay2-php-sdk