docs: migrate to travis-ci.com

Author: danez

README.md

@@ -3,7 +3,7 @@
 </p>
 
 <p align="center">
-  <a href="https://travis-ci.org/researchgate/react-intersection-observer"><img alt="Build Status" src="https://travis-ci.org/researchgate/react-intersection-observer.svg?branch=master"></a>
+  <a href="https://travis-ci.com/researchgate/react-intersection-observer"><img alt="Build Status" src="https://travis-ci.com/researchgate/react-intersection-observer.svg?branch=master"></a>
   <a href="https://codecov.io/gh/researchgate/react-intersection-observer"><img alt="Codecov" src="https://img.shields.io/codecov/c/github/researchgate/react-intersection-observer.svg"></a>
   <a href="https://www.npmjs.com/package/@researchgate/react-intersection-observer"><img alt="NPM version" src="https://img.shields.io/npm/v/@researchgate/react-intersection-observer.svg"></a>
   <a href="https://www.npmjs.com/package/@researchgate/react-intersection-observer"><img alt="Dowloads per week" src="https://img.shields.io/npm/dw/@researchgate/react-intersection-observer.svg"></a>