delete the discord badge (#507)

delete the discord badge
because it has expired a long time ago

Author: liqul

README.md

@@ -4,7 +4,6 @@
 
 <div align="center">
 
-[![Discord Follow](https://dcbadge.vercel.app/api/server/Z56MXmZgMb?style=flat)](https://discord.gg/Z56MXmZgMb) &ensp;
 ![Python Version](https://img.shields.io/badge/Python-3776AB?&logo=python&logoColor=white-blue&label=3.10%20%7C%203.11)&ensp;
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)&ensp;
 ![Welcome](https://img.shields.io/badge/contributions-welcome-brightgreen.svg?style=flat)