chore: travis ci badge point to master branch (#2616)

Author: daviddias

README.md

@@ -20,7 +20,7 @@
 
 <p align="center">
   <a href="https://github.com/ipfs/interface-ipfs-core"><img src="https://img.shields.io/badge/interface--ipfs--core-API%20Docs-blue.svg"></a>
-  <a href="https://travis-ci.com/ipfs/js-ipfs"><img src="https://badgen.net/travis/ipfs/js-ipfs" /></a>
+  <a href="https://travis-ci.com/ipfs/js-ipfs?branch=master"><img src="https://badgen.net/travis/ipfs/js-ipfs?branch=master" /></a>
   <a href="https://codecov.io/gh/ipfs/js-ipfs"><img src="https://badgen.net/codecov/c/github/ipfs/js-ipfs" /></a>
   <a href="https://bundlephobia.com/result?p=ipfs"><img src="https://badgen.net/bundlephobia/minzip/ipfs"></a>
   <a href="https://david-dm.org/ipfs/js-ipfs"><img src="https://david-dm.org/ipfs/js-ipfs.svg?style=flat" /></a>