We updated our RSA SSH host key
At approximately 05:00 UTC on March 24, out of an abundance of caution, we replaced our RSA SSH host key used to secure Git operations for GitHub.com.
https://github.blog/2023-03-23-we-updated-our-rsa-ssh-host-key/
GitHub、誤公開した RSA SSH ホスト鍵を更新
https://security.srad.jp/story/23/03/25/0755251/