W: GPG error: https://packages.sury.org/php stretch InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY AC0E47584A7A714D W: The repository ‘https://packages.sury.org/php stretch InRelease’ is not signed. N: Data from such a repository can’t be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details.