Update build badge

README.md

@@ -3,7 +3,7 @@
 </p>
 
 <p align="center">
-<a href="https://travis-ci.org/onevcat/Kingfisher"><img src="https://img.shields.io/travis/onevcat/Kingfisher/master.svg"></a>
+<a href="https://github.com/onevcat/Kingfisher/actions?query=workflow%3Abuild"><img src="https://github.com/onevcat/kingfisher/workflows/build/badge.svg?branch=master"></a>
 <a href="http://onevcat.github.io/Kingfisher/"><img src="https://img.shields.io/cocoapods/v/Kingfisher.svg?style=flat"></a>
 <a href="https://github.com/Carthage/Carthage/"><img src="https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat"></a>
 <a href="https://swift.org/package-manager/"><img src="https://img.shields.io/badge/SPM-supported-DE5C43.svg?style=flat"></a>