ssh: connect to host github.com port 22: Connection refused是连接github.com的端口号22拒绝连接
22端口拒绝连接，我们可以使用443端口号进行连接

解决方案

1. 打开git bash窗口
2. 输入vim ~/.ssh/config
3. 添加如下字段

   如果没有config 文件就新建一个
   Host github.com
   Hostname ssh.github.com
   Port 443
   

4. 测试连接

   ssh -T [email protected]
   

   如果出现以下内容，输入yes即可
   The authenticity of host ‘[ssh.github.com]:443 ([20.205.243.160]:443)’ can’t be established.
   ECDSA key fingerprint is SHA256:p2QAMXNIC1TJYWeIOttrVc98/R1BUFWu3/LiyKgUfQM.
   Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
   最终显示Hi chengyun-pg! You’ve successfully authenticated, but GitHub does not provide shell access.，可能会比较慢，耐心等待。