我收到此警告/错误
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 71EB474019940E11
Reading package lists... Done
W: GPG error: https://repo.protonvpn.com/debian stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 71EB474019940E11
E: The repository 'https://repo.protonvpn.com/debian stable InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
当我跑步时，sudo apt …
apt ×1