Email verification service changed from SendGrid to Gmail. I received complaints about SendGrid not friendly to individual users and thus I changed default / sample email verification method to Gmail. You only need a valid Gmail account to make email verification work. Just set up 2-step verification and generate an app-specific password for this password manager.
Except for above email verification change, this release is same with 11.00. So to upgrade from 11.00, you just need to overwrite source code files.