readme: fix ci badge

Author: Equim-chan

README.md

@@ -10,7 +10,7 @@
 
 # filebrowser
 
-[![CircleCI](https://img.shields.io/circleci/project/github/filebrowser/filebrowser.svg?style=flat-square)](https://circleci.com/gh/filebrowser/filebrowser)
+[![Travis](https://img.shields.io/travis//filebrowser/filebrowser.svg?style=flat-square)](https://travis-ci.org/filebrowser/filebrowser)
 [![Go Report Card](https://goreportcard.com/badge/github.com/filebrowser/filebrowser?style=flat-square)](https://goreportcard.com/report/github.com/filebrowser/filebrowser)
 [![Documentation](https://img.shields.io/badge/godoc-reference-blue.svg?style=flat-square)](http://godoc.org/github.com/filebrowser/filebrowser)
 [![Version](https://img.shields.io/github/release/filebrowser/filebrowser.svg?style=flat-square)](https://github.com/filebrowser/filebrowser/releases/latest)