git push时出现以下问题：

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@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
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IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
SHA256:uNiVztksCsDhcc0u9e8BujQXVUpKZIDTMczCvj3tD2s.
Please contact your system administrator.
Add correct host key in /home/amaranth/.ssh/known_hosts to get rid of this message.
Offending RSA key in /home/amaranth/.ssh/known_hosts:4
Host key for github.com has changed and you have requested strict checking.
Host key verification failed.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

这个错误表示你尝试通过SSH连接到GitHub时，SSH客户端检测到主机密钥发生了变化。这通常是因为GitHub服务器的SSH主机密钥被更新了，而你的SSH客户端仍然使用旧的主机密钥来验证服务器。由于你启用了严格的主机密钥检查（strict checking），SSH客户端会拒绝连接。