Removed gitter badge

Author: kojix2

README.md

@@ -2,7 +2,6 @@
 
 [![Gem Version](https://img.shields.io/gem/v/ruby-gr?color=brightgreen)](https://rubygems.org/gems/ruby-gr)
 [![CI](https://github.com/red-data-tools/GR.rb/workflows/CI/badge.svg)](https://github.com/red-data-tools/GR.rb/actions)
-[![Gitter Chat](https://badges.gitter.im/red-data-tools/en.svg)](https://gitter.im/red-data-tools/en)
 [![Docs Latest](https://img.shields.io/badge/docs-latest-blue.svg)](https://red-data-tools.github.io/GR.rb/)
 [![Lines of Code](https://img.shields.io/endpoint?url=https%3A%2F%2Ftokei.kojix2.net%2Fbadge%2Fgithub%2Fred-data-tools%2FGR.rb%2Flines)](https://tokei.kojix2.net/github/red-data-tools/GR.rb)