Replace ActionCable broadcast call with simple redis publish

app/lib/feed_manager.rb

@@ -39,7 +39,7 @@ class FeedManager
 
   def broadcast(timeline_id, options = {})
     options[:queued_at] = (Time.now.to_f * 1000.0).to_i
-    ActionCable.server.broadcast("timeline:#{timeline_id}", options)
+    redis.publish("timeline:#{timeline_id}", Oj.dump(options))
   end
 
   def trim(type, account_id)