Update README.md

Author: sroebert

README.md

@@ -2,7 +2,7 @@
 
 Non-blocking, event-driven Swift client for MQTT ([3.1.1](http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html)) build on [SwiftNIO](https://github.com/apple/swift-nio).
 
-[![Build Status](https://travis-ci.org/sroebert/mqtt-nio.svg?branch=master)](https://travis-ci.org/sroebert/mqtt-nio)
+![test](https://github.com/sroebert/mqtt-nio/workflows/test/badge.svg)
 
 ## Installation