Cannot upgrade to latest version of thunderbird 78

I need to upgrade to thunderbird 78. I currently have 68 running Ubuntu 20.04. I tried:

sudo add-apt-repository ppa:ubuntu-mozilla-daily/ppa

and then update and upgrade but Ubuntu keeps on telling me:

thunderbird is already the newest version (1:68.10.0+build1-0ubuntu0.20.04.1).

Best

The Ubuntu Desktop Team is currently working on packaging Thunderbird 78. Be patient.

You don't need to add a PPA. The Ubuntu Desktop and Ubuntu Security teams regularly update Firefox and Thunderbird in all supported releases of Ubuntu.

The specific output you received means that nobody uploaded Thunderbird 78 to that PPA.

You can use this ppa which provides the packaged version with no deps like libc6. Thunderbird is actually locked to version 68 on focal, and on 20.10 it is on version 78, but it forces using libc6 2.32.

Any way just use it from here https://www.ubuntuupdates.org/ppa/ubuntu_mozilla_security?dist=focal

sudo add-apt-repository ppa:ubuntu-mozilla-security/ppa 
sudo apt-get update
sudo apt-get install thunderbird

You may also install thunderbird-fr to use French translation for example.

If you real need new version, you can use Snap Store

https://snapcraft.io/thunderbird