Don't pass retry option to Sidekiq

* This would override whatever default is configured in Sidekiq
  system-wide, and retry is true by default anyway.

activejob/lib/active_job/queue_adapters/sidekiq_adapter.rb

@@ -21,8 +21,7 @@ def enqueue(job) #:nodoc:
           Sidekiq::Client.push \
             'class' => JobWrapper,
             'queue' => job.queue_name,
-            'args'  => [ job.serialize ],
-            'retry' => true
+            'args'  => [ job.serialize ]
         end
 
         def enqueue_at(job, timestamp) #:nodoc:
@@ -30,7 +29,6 @@ def enqueue_at(job, timestamp) #:nodoc:
             'class' => JobWrapper,
             'queue' => job.queue_name,
             'args'  => [ job.serialize ],
-            'retry' => true,
             'at'    => timestamp
         end
       end