'main' has been the primary branch since December 2020 when the project
underwent a major refactoring that brought about the unification of the
two themes into a single code base.

The packages 'modus-operandi-theme' and 'modus-vivendi-theme' were
deleted from GNU ELPA yesterday (see Emacs bug#49574), following a ~3
month period during which they would unconditionally pull in the new
'modus-themes' package.

This formally fixes issue 174 by Damien Cassou:
<#174>.