Subsonic 6.0beta1 was still GPL and then changed to "something".

https://github.com/Libresonic/libresonic#history

PR: 213299
Submitted by: Allison Nicole Reid <root at cooltrainer org>
Approved by: adamw (Phabricator), jpaetzel (IRC)
Differential Revision: https://reviews.freebsd.org/D11444