gpg key expired when doing 'apt-get update'
If you're seeing something like this:
1W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://packagecloud.io/github/git-lfs/ubuntu xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6B05F25D762E3157
2W: Failed to fetch https://packagecloud.io/github/git-lfs/ubuntu/dists/xenial/InRelease The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6B05F25D762E3157
3W: Some index files failed to download. They have been ignored, or old ones used instead.
Solution is to run
1sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 6B05F25D762E3157