当我尝试升级 Ubuntu 时，我不断收到以下错误：
Hit http://security.ubuntu.com/ubuntu hirsute-security InRelease
Err https://download.docker.com/linux/ubuntu groovy InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7EA0A9C3F273FCD8
Fetched 43.3 kB in 0s (0 B/s)
Hit http://archive.ubuntu.com/ubuntu hirsute InRelease
Hit http://archive.ubuntu.com/ubuntu hirsute-updates InRelease
Get:1 https://download.docker.com/linux/ubuntu groovy InRelease [43.3 kB]
Err https://download.docker.com/linux/ubuntu groovy InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7EA0A9C3F273FCD8
Hit http://security.ubuntu.com/ubuntu hirsute-security InRelease
Fetched 43.3 kB in 0s (0 B/s)
Error during update
A problem occurred during the update. This is usually some sort of
network problem, please check your network connection and retry.
Restoring original system state
Aborting
Reading package lists... Done
Building dependency tree
Reading state information... Done
有什么建议么？
我曾尝试将镜像更改为有线网络，但每次都会出现上述完全相同的错误。