Add An Simple testing framework: Pest

README.md

 * [Mink](http://mink.behat.org/en/latest/) - Web acceptance testing.
 * [Mockery](https://github.com/mockery/mockery) - A mock object library for testing.
 * [ParaTest](https://github.com/paratestphp/paratest) - A parallel testing library for PHPUnit.
+* [Pest](https://pestphp.com/) - A Testing Framework with a focus on simplicity. It was carefully crafted to bring the joy of testing to PHP.
 * [Peridot](https://github.com/peridot-php/peridot) - An event driven test framework.
 * [Phake](https://github.com/mlively/Phake) - Another mock object library for testing.
 * [Pho](https://github.com/danielstjules/pho) - Another behaviour driven development testing framework.