Comment 0 for bug 1949605

Similarly to bug #1895643, which was about upgrading thunderbird from 68 to 78 in all supported Ubuntu releases, this bug is to track the update from thunderbird 78 to 91 in hirsute, focal and bionic.

The rationale is that series 78 will soon be out of support (the last release, 78.14.0, was made public on September 7, 2021).

Thunderbird follows the Firefox ESR release cycle, and the next/current series is 91 (already available in impish and jammy).