Gem `queue_classic` does not support JRuby

Gemfile

@@ -44,7 +44,7 @@ gem 'resque-scheduler', require: false
 gem 'sidekiq', require: false
 gem 'sucker_punch', require: false
 gem 'delayed_job', require: false
-gem 'queue_classic', require: false
+gem 'queue_classic', require: false, platforms: :ruby
 gem 'sneakers', '0.1.1.pre', require: false
 gem 'que', require: false
 gem 'backburner', require: false