message: Update version badge on README.md
diff: <h2 align="center">Authentication & Storage for Hasura</h2>
  <p align="center">
  - <img src="https://img.shields.io/badge/version-2.0.0-blue.svg?cacheSeconds=2592000" />
  + <img src="https://img.shields.io/badge/version-2.2.1-blue.svg?cacheSeconds=2592000" />
  <a href="LICENSE">
  <img src="https://img.shields.io/badge/license-MIT-yellow.svg" alt="license: MIT" />
  </a>
  