style(rubocop): fix all safe auto correctable offenses

app/jobs/expire_held_messages_job.rb

@@ -1,12 +1,14 @@
 class ExpireHeldMessagesJob < Postal::Job
+
   def perform
     Server.all.each do |server|
-      messages = server.message_db.messages(:where => {
-        :status => 'Held',
-        :hold_expiry => {:less_than => Time.now.to_f}
+      messages = server.message_db.messages(where: {
+        status: "Held",
+        hold_expiry: { less_than: Time.now.to_f }
       })
 
       messages.each(&:cancel_hold)
     end
   end
+
 end