The following signatures couldn't be verified because the public key is not available

[Error fix] Solved 'The repository 'https://packagecloud.io/shiftkey/desktop/any any InRelease' is not signed.': The following signatures couldn't be verified because the public key is not available

# Problem when I was entered the command, I got a that Error(E): $ sudo apt update Hit:1 http://packages.microsoft.com/repos/code stable InRelease ... Get:10 https://packagecloud.io/shiftkey/desktop/any any InRelease [24.4 kB] Hit:12 http://packages.ros.org/ros/ubuntu focal InRelease Err:10 https://packagecloud.io/shiftkey/desktop/any any InRelease The following signatures couldn't be verified b..