message: (chore) - add spectrum badge
diff: <a href="https://bundlephobia.com/result?p=@urql/exchange-graphcache">
  <img alt="Minified gzip size" src="https://img.shields.io/bundlephobia/minzip/@urql/exchange-graphcache.svg?label=gzip%20size" />
  </a>
  +<a href="https://spectrum.chat/urql">
  + <img alt="Spectrum badge" src="https://withspectrum.github.io/badge/badge.svg" />
  +</a>
  <br />
  <br />
  