Debian 11安装MySQL Server时遭遇签名验证错误及安装失败问题求助

大家好，我在Debian 11上尝试通过apt添加MySQL仓库来安装MySQL Server，操作步骤如下：

首先下载MySQL的apt配置包：

wget https://dev.mysql.com/get/mysql-apt-config_0.8.22-1_all.deb

接着安装这个配置包：

sudo dpkg -i mysql-apt-config_0.8.22-1_all.deb

但当我执行更新命令时：

sudo apt update

出现了签名验证失败的错误：

Err:4 http://repo.mysql.com/apt/debian bullseye InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY B7B3B788A8D3785C

之后我尝试安装MySQL Server：

sudo apt-get install mysql-server

又遇到了安装失败的提示：

Package mysql-server is not available, but is referred to by another
package. This may mean that the package is missing, has been
obsoleted, or is only available from another source

我猜测这可能和我在BIOS里开启了“虚拟化”保护选项有关？不过不确定具体原因，想请教大家怎么给MySQL的仓库签名来解决这个问题呀？

备注：内容来源于stack exchange，提问作者Raul-Angel García