update thunderbird to 78.7.0
Release Notes (soon):
https://www.thunderbird.net/en-US/thunderbird/78.7.0/releasenotes/
MFH: r562507 r562651
update thunderbird to 78.7.0 (rc1)
Release Notes (soon):
https://www.thunderbird.net/en-US/thunderbird/78.7.0/releasenotes/
update thunderbird to 78.7.0 (rc2)
Release Notes (soon):
https://www.thunderbird.net/en-US/thunderbird/78.7.0/releasenotes/