meta: remove CI badge (#15286)

Co-authored-by: Rik Smale <13023439+WikiRik@users.noreply.github.com>

README.md

@@ -4,7 +4,6 @@
 </p>
 
 [![npm version](https://badgen.net/npm/v/@sequelize/core)](https://www.npmjs.com/package/@sequelize/core)
-[![Build Status](https://github.com/sequelize/sequelize/workflows/CI/badge.svg)](https://github.com/sequelize/sequelize/actions?query=workflow%3ACI)
 [![npm downloads](https://badgen.net/npm/dm/@sequelize/core)](https://www.npmjs.com/package/@sequelize/core)
 [![contributors](https://img.shields.io/github/contributors/sequelize/sequelize)](https://github.com/sequelize/sequelize/graphs/contributors)
 [![Open Collective](https://img.shields.io/opencollective/backers/sequelize)](https://opencollective.com/sequelize#section-contributors)