refactor: remove README.md's broken build badge (#2183)

Author: hamirmahal

README.md

@@ -6,7 +6,6 @@
 [![Mozilla Add-on](https://badgen.net/amo/users/ext-saladict?icon=firefox&color=ff9500)](https://addons.mozilla.org/firefox/addon/ext-saladict/)
 [![Mozilla Add-on](https://badgen.net/amo/stars/ext-saladict?icon=firefox&color=ff9500)](https://addons.mozilla.org/firefox/addon/ext-saladict/)
 
-[![Build Status](https://travis-ci.com/crimx/ext-saladict.svg)](https://travis-ci.com/crimx/ext-saladict)
 [![Commitizen friendly](https://img.shields.io/badge/commitizen-friendly-brightgreen.svg?maxAge=2592000)](http://commitizen.github.io/cz-cli/)
 [![Conventional Commits](https://img.shields.io/badge/Conventional%20Commits-1.0.0-brightgreen.svg?maxAge=2592000)](https://conventionalcommits.org)
 [![Standard - JavaScript Style Guide](https://img.shields.io/badge/code_style-standard-brightgreen.svg?maxAge=2592000)](https://standardjs.com/)