(#200) Updated build status badges in README.md

Author: s1hofmann

README.md

@@ -1,9 +1,9 @@
 # nut.js (Native UI Toolkit) 
 
-|	|Travis	|Appveyor	|
-|:-:	|:-:	|:-:		|
-|Master |[![Build Status](https://travis-ci.com/nut-tree/nut.js.svg?branch=master)](https://travis-ci.com/nut-tree/nut.js)|[![Build status](https://ci.appveyor.com/api/projects/status/iohwxc5t46gcuvby/branch/master?svg=true)](https://ci.appveyor.com/project/s1hofmann/nut-js/branch/master)|
-|Develop|[![Build Status](https://travis-ci.com/nut-tree/nut.js.svg?branch=develop)](https://travis-ci.com/nut-tree/nut.js)|[![Build status](https://ci.appveyor.com/api/projects/status/iohwxc5t46gcuvby/branch/develop?svg=true)](https://ci.appveyor.com/project/s1hofmann/nut-js/branch/develop)|
+|	|GitHub Actions|
+|:-:	|:-:	|
+|Master |![Run CI](https://github.com/nut-tree/nut.js/workflows/Run%20CI/badge.svg?branch=master)|
+|Develop|![Run CI](https://github.com/nut-tree/nut.js/workflows/Run%20CI/badge.svg?branch=develop)|
 
 ![Supported node versions](https://img.shields.io/badge/node-v10.x%20--%20v14.x-green)
 [![SonarCloud badge](https://sonarcloud.io/api/project_badges/measure?project=nut-tree%3Anut.js&metric=alert_status)](https://sonarcloud.io/dashboard?id=nut-tree%3Anut.js)