Use `bulk_perform_async` to schedule issue due emails

app/workers/issue_due_scheduler_worker.rb

@@ -3,8 +3,8 @@ class IssueDueSchedulerWorker
   include CronjobQueue
 
   def perform
-    Issue.opened.due_tomorrow.group(:project_id).pluck(:project_id).each do |project_id|
-      MailScheduler::IssueDueWorker.perform_async(project_id)
-    end
+    project_ids = Issue.opened.due_tomorrow.group(:project_id).pluck(:project_id).map { |id| [id] }
+
+    MailScheduler::IssueDueWorker.bulk_perform_async(project_ids)
   end
 end

spec/workers/issue_due_scheduler_worker_spec.rb

@@ -14,8 +14,7 @@ describe IssueDueSchedulerWorker do
       create(:issue, :closed, project: project_closed_issue, due_date: Date.tomorrow)
       create(:issue, :opened, project: project_issue_due_another_day, due_date: Date.today)
 
-      expect(MailScheduler::IssueDueWorker).to receive(:perform_async).with(project1.id)
-      expect(MailScheduler::IssueDueWorker).to receive(:perform_async).with(project2.id)
+      expect(MailScheduler::IssueDueWorker).to receive(:bulk_perform_async).with([[project1.id], [project2.id]])
 
       described_class.new.perform
     end