Loadable SQLite3 extension (libnusqlite3.so) built from the nunicode
library. Registers Unicode-aware NUxxxx and NUxxxx_NOCASE collations,
named after the Unicode version implemented by the nunicode release,
overrides upper(), lower() and like(), and adds unaccent(). Used by
applications such as Audiobookshelf for locale-correct sorting and
searching.

The upstream README lists the Unicode version for each release:
https://bitbucket.org/alekseyt/nunicode/