remove travis, appveyor from project (#22007)

Author: wing328

CI/.travis.yml.bash

@@ -16,9 +16,7 @@
 <div align="center">
 
 [Master](https://github.com/OpenAPITools/openapi-generator/tree/master) (`7.16.0`):
-[![Build Status](https://api.travis-ci.com/OpenAPITools/openapi-generator.svg?branch=master&status=passed)](https://app.travis-ci.com/github/OpenAPITools/openapi-generator/builds)
 [![Integration Test2](https://circleci.com/gh/OpenAPITools/openapi-generator.svg?style=shield)](https://circleci.com/gh/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)
 [![Bitrise](https://img.shields.io/bitrise/4a2b10a819d12b67/master?label=bitrise%3A%20Swift+4,5&token=859FMDR8QHwabCzwvZK6vQ)](https://app.bitrise.io/app/4a2b10a819d12b67)
 
 </div>