W: GPG error: https://cli.github.com/packages bionic InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY C99B11DEB97541F0 code example
Example: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 6494C6D6997C215E