docs(readme): fix badge style

Author: azdanov

README.md

@@ -1,4 +1,4 @@
-# PHP Interview Exercises · [![Build Status](https://img.shields.io/travis/com/azdanov/php-interview-exercises/master.svg?logo=travis)](https://travis-ci.com/azdanov/php-interview-exercises) [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-blue.svg?logo=github)](http://makeapullrequest.com) [![Exercise Count](https://img.shields.io/endpoint.svg?url=https://php-interview-questions-counter.netlify.com/.netlify/functions/count)](./exercises) [![All Contributors](https://img.shields.io/badge/all_contributors-5-orange.svg?style=flat-square)](#contributors)
+# PHP Interview Exercises · [![Build Status](https://img.shields.io/travis/com/azdanov/php-interview-exercises/master.svg?logo=travis)](https://travis-ci.com/azdanov/php-interview-exercises) [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-blue.svg?logo=github)](http://makeapullrequest.com) [![Exercise Count](https://img.shields.io/endpoint.svg?url=https://php-interview-questions-counter.netlify.com/.netlify/functions/count)](./exercises) [![All Contributors](https://img.shields.io/badge/all_contributors-5-orange.svg)](#contributors)
 
 A number of exercises to practice whiteboard interview questions in PHP.