Update Laravel version (#1008)

Laravel 6 was released and it is a LTS version

README.md

 
 * [Aura Framework](http://auraphp.com/framework/) - A framework built from independent components.
 * [CakePHP](https://cakephp.org/) - A rapid application development framework (CP).
-* [Laravel 5](https://laravel.com/) - Another PHP framework (L5).
+* [Laravel 6](https://laravel.com/) - Another PHP framework (L6).
 * [Nette](https://nette.org) - Another framework comprised of individual components.
 * [Phalcon](https://phalconphp.com/en/) - A framework implemented as a C extension.
 * [PPI Framework 2](https://github.com/ppi) - An interoperability framework.
 * [Cake ORM](https://github.com/cakephp/orm) - Object-Relational Mapper, implemented using the DataMapper pattern (CP).
 * [Doctrine Extensions](https://github.com/Atlantic18/DoctrineExtensions) - A collection of Doctrine behavioural extensions.
 * [Doctrine](https://www.doctrine-project.org/) - A comprehensive DBAL and ORM.
-* [Eloquent](https://github.com/illuminate/database) - A simple ORM (L5).
+* [Eloquent](https://github.com/illuminate/database) - A simple ORM (L6).
 * [Pomm](https://github.com/chanmix51/Pomm) - An Object Model Manager for PostgreSQL.
 * [ProxyManager](https://github.com/Ocramius/ProxyManager) - A set of utilities to generate proxy objects for data mappers.
 * [RedBean](https://redbeanphp.com/index.php) - A lightweight, configuration-less ORM.