Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1
I opted into the Git repo instead of the zip archive since I cannot get
consistent results with it (with the '--rounds=3' flag). The package is
tested to be built in x86_64. Other architectures are yet to be
confirmed since I cannot build it successfully.