[DRE-maint] Bug#1029139: Please include Java/JRuby native extension

[Jérôme Charaoui]

I've submitted a MR on Salsa implementing this change:

https://salsa.debian.org/ruby-team/ruby-concurrent/-/merge_requests/1

Please review and merge at your earliest convenience.

If you prefer, as a member of the Ruby team, I can also take care of 
performing the merge and uploading a new package revision.

Thanks!

-- Jérôme