Remove Slack badge from README

Removed Slack badge link from README.

Author: adrolli

README.md

@@ -26,7 +26,6 @@
     <a href="https://hosted.weblate.org/engage/moox/"><img src="https://hosted.weblate.org/widgets/moox/-/svg-badge.svg" alt="Translation status" /></a>
     <a href="https://allcontributors.org/"><img alt="All Contributors" src="https://img.shields.io/github/all-contributors/mooxphp/moox"></a>
     <a href="https://github.com/mooxphp/moox-app-components/blob/main/LICENSE.md"><img alt="License" src="https://img.shields.io/github/license/mooxphp/moox?color=blue&label=license"></a>
-    <a href="https://mooxphp.slack.com/"><img alt="Slack" src="https://img.shields.io/badge/Slack-Moox-blue?logo=slack"></a>
     <br>
     <br>
 </p>