Drop Travis (#1267)

* Update README.md

* Update .travis.yml

Author: johnnyreilly

.travis.yml

@@ -1,3 +1,4 @@
+# Travis is no longer used - this file will be removed in future
 os:
   - linux
 addons:

README.md

@@ -2,7 +2,6 @@
 
 [![npm version](https://img.shields.io/npm/v/ts-loader.svg)](https://www.npmjs.com/package/ts-loader)
 ![GitHub build)](https://github.com/TypeStrong/ts-loader/workflows/Continuous%20Integration%20(build%20and%20test)/badge.svg)
-[![Travis build](https://travis-ci.org/TypeStrong/ts-loader.svg?branch=master)](https://travis-ci.org/TypeStrong/ts-loader)
 [![Downloads](http://img.shields.io/npm/dm/ts-loader.svg)](https://npmjs.org/package/ts-loader)
 [![node version](https://img.shields.io/node/v/ts-loader.svg)](https://www.npmjs.com/package/ts-loader)
 [![code style: prettier](https://img.shields.io/badge/code_style-prettier-ff69b4.svg)](https://github.com/prettier/prettier)