It looks like this answer on AskUbuntu should fix the issue.
Apparently this is caused by a GPG signing key, perhaps for Albert Launcher?
Just delete the mentioned manuelschneid3r key from your list of trusted keys.
sudo rm /etc/apt/trusted.gpg.d/home:manuelschneid3r.*
If the key is indeed for the Albert Launcher, you should be able to safely re-add it by ...