data: Tweak AppData string to no longer need new translations

Commit b55388bea5a60bb7a36aa63151ff11ff5ffb3ea3 broke the string
freeze. Sorry.

The <summary> element is needed to get hitori.appdata.xml to pass
validation with recent versions of appstream-glib, so some string is
needed here.
Release version 3.14.2.1