Adding codecov badge/config

Author: josbeir

README.md

@@ -1,5 +1,6 @@
 [![PHPStan Level 8](https://img.shields.io/badge/PHPStan-level%208-brightgreen)](https://github.com/josbeir/cakephp-synapse)
 [![Build Status](https://github.com/josbeir/cakephp-synapse/actions/workflows/ci.yml/badge.svg)](https://github.com/josbeir/cakephp-synapse/actions)
+[![codecov](https://codecov.io/github/josbeir/cakephp-synapse/graph/badge.svg?token=4VGWJQTWH5)](https://codecov.io/github/josbeir/cakephp-synapse)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 [![PHP Version](https://img.shields.io/badge/php-8.2%2B-blue.svg)](https://www.php.net/releases/8.2/en.php)
 [![CakePHP Version](https://img.shields.io/badge/CakePHP-5.2%2B-red.svg)](https://cakephp.org/)