习惯性的apt update时，报错了：
W: GPG error: http://repo.mysql.com/apt/debian bullseye InRelease: The following signatures couldn't be verified because the public keylable: NO_PUBKEY B7B3B788A8D3785C
E: The repository 'http://repo.mysql.com/apt/debian bullseye InRelease' is not signed.需要安装mysql-apt-config.deb，在https://dev.mysql.com/downloads/repo/apt/下载并安装，GPG Key会在安装过程中重新配置。
最后重新执行apt update即可。