chore: fix build badge

Author: atymic

README.md

@@ -2,7 +2,7 @@
 
 [![Latest Version on Packagist](https://img.shields.io/packagist/v/laravel-notification-channels/twilio.svg?style=flat-square)](https://packagist.org/packages/laravel-notification-channels/twilio)
 [![Software License](https://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat-square)](LICENSE.md)
-[![Build Status](https://img.shields.io/travis/laravel-notification-channels/twilio/master.svg?style=flat-square)](https://travis-ci.org/laravel-notification-channels/twilio)
+[![Build Status](https://img.shields.io/github/workflow/status/laravel-notification-channels/twilio/PHP?style=flat-square)](https://travis-ci.org/laravel-notification-channels/twilio)
 [![StyleCI](https://styleci.io/repos/65543339/shield)](https://styleci.io/repos/65543339)
 [![Quality Score](https://img.shields.io/scrutinizer/g/laravel-notification-channels/twilio.svg?style=flat-square)](https://scrutinizer-ci.com/g/laravel-notification-channels/twilio)
 [![Code Coverage](https://img.shields.io/scrutinizer/coverage/g/laravel-notification-channels/twilio/master.svg?style=flat-square)](https://scrutinizer-ci.com/g/laravel-notification-channels/twilio/?branch=master)