Set badge to 9.x

Author: yajra

README.md

@@ -1,6 +1,6 @@
 # Laravel DataTables Buttons Plugin
 
-[![Laravel 5.x](https://img.shields.io/badge/Laravel-5.x-orange.svg)](http://laravel.com)
+[![Laravel 9.x](https://img.shields.io/badge/Laravel-9.x-orange.svg)](http://laravel.com)
 [![Latest Stable Version](https://img.shields.io/packagist/v/yajra/laravel-datatables-buttons.svg)](https://packagist.org/packages/yajra/laravel-datatables-buttons)
 [![Build Status](https://travis-ci.org/yajra/laravel-datatables-buttons.svg?branch=master)](https://travis-ci.org/yajra/laravel-datatables-buttons)
 [![Scrutinizer Code Quality](https://scrutinizer-ci.com/g/yajra/laravel-datatables-buttons/badges/quality-score.png?b=master)](https://scrutinizer-ci.com/g/yajra/laravel-datatables-buttons/?branch=master)