Remove gitter link

According to the chat history on gitter, the last activity was on Sep 29 2022.
GIU development happens on GitHub (by issues and discussions) now.
In my opinion we shouldn't keep that link on top of the README.

README.md

@@ -1,6 +1,6 @@
 # giu
 
-[![Join the chat at https://gitter.im/AllenDang-giu/community](https://badges.gitter.im/AllenDang-giu/community.svg)](https://gitter.im/AllenDang-giu/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+<!--[![Join the chat at https://gitter.im/AllenDang-giu/community](https://badges.gitter.im/AllenDang-giu/community.svg)](https://gitter.im/AllenDang-giu/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)-->
 [![Go Report Card](https://goreportcard.com/badge/github.com/AllenDang/giu)](https://goreportcard.com/report/github.com/AllenDang/giu)
 ![Build Status](https://github.com/AllenDang/giu/actions/workflows/build.yml/badge.svg)
 [![Go Reference](https://pkg.go.dev/badge/github.com/AllenDang/giu.svg)](https://pkg.go.dev/github.com/AllenDang/giu)