Update badges

Author: ackintosh

README.md

@@ -2,16 +2,11 @@
 
 <div align="center">
 
-[Master](https://github.com/OpenAPITools/openapi-generator/tree/master) (`3.0.3`): [![Build Status](https://img.shields.io/travis/OpenAPITools/openapi-generator/master.svg?label=Integration%20Test)](https://travis-ci.org/OpenAPITools/openapi-generator)
+[Master](https://github.com/OpenAPITools/openapi-generator/tree/master) (`3.1.0`): [![Build Status](https://img.shields.io/travis/OpenAPITools/openapi-generator/master.svg?label=Integration%20Test)](https://travis-ci.org/OpenAPITools/openapi-generator)
 [![Integration Test2](https://circleci.com/gh/OpenAPITools/openapi-generator.svg?style=shield)](https://circleci.com/gh/OpenAPITools/openapi-generator)
 [![Run Status](https://api.shippable.com/projects/5af6bf74e790f4070084a115/badge?branch=master)](https://app.shippable.com/github/OpenAPITools/openapi-generator)
 [![Windows Test](https://ci.appveyor.com/api/projects/status/github/openapitools/openapi-generator?branch=master&svg=true&passingText=Windows%20Test%20-%20OK&failingText=Windows%20Test%20-%20Fails)](https://ci.appveyor.com/project/WilliamCheng/openapi-generator-wh2wu)
 
-[`3.1.x`](https://github.com/OpenAPITools/openapi-generator/tree/3.1.x) branch: [![Build Status](https://img.shields.io/travis/OpenAPITools/openapi-generator/3.1.x.svg?label=Integration%20Test)](https://travis-ci.org/OpenAPITools/openapi-generator)
-[![Integration Test2](https://circleci.com/gh/OpenAPITools/openapi-generator/tree/3.1.x.svg?style=shield)](https://circleci.com/gh/OpenAPITools/openapi-generator)
-[![Run Status](https://api.shippable.com/projects/5af6bf74e790f4070084a115/badge?branch=3.1.x)](https://app.shippable.com/github/OpenAPITools/openapi-generator)
-[![Windows Test](https://ci.appveyor.com/api/projects/status/github/openapitools/openapi-generator?branch=3.1.x&svg=true&passingText=Windows%20Test%20-%20OK&failingText=Windows%20Test%20-%20Fails)](https://ci.appveyor.com/project/WilliamCheng/openapi-generator-wh2wu)
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 [`4.0.x`](https://github.com/OpenAPITools/openapi-generator/tree/4.0.x) branch: [![Build Status](https://img.shields.io/travis/OpenAPITools/openapi-generator/4.0.x.svg?label=Integration%20Test)](https://travis-ci.org/OpenAPITools/openapi-generator)
 [![Integration Test2](https://circleci.com/gh/OpenAPITools/openapi-generator/tree/4.0.x.svg?style=shield)](https://circleci.com/gh/OpenAPITools/openapi-generator)
 [![Run Status](https://api.shippable.com/projects/5af6bf74e790f4070084a115/badge?branch=4.0.x)](https://app.shippable.com/github/OpenAPITools/openapi-generator)