chore: Remove Travis-CI build indicator

Author: inexorabletash

README.md

@@ -1,8 +1,6 @@
 Indexed DB
 ----------
 
-[![Build Status](https://travis-ci.com/w3c/IndexedDB.svg?branch=main)](https://travis-ci.com/w3c/IndexedDB)
-
 This is a repository for the development of the Indexed Database (Third Edition) specification.
 * [Latest Editor's Draft](https://w3c.github.io/IndexedDB/)