Quarantine this flaky test

See
https://gitlab.com/gitlab-org/gitlab-ce/issues/62760

spec/models/ci/pipeline_schedule_spec.rb

@@ -128,7 +128,7 @@ describe Ci::PipelineSchedule do
     context 'when pipeline schedule runs every minute' do
       let(:pipeline_schedule) { create(:ci_pipeline_schedule, :every_minute) }
 
-      it "updates next_run_at to the sidekiq worker's execution time" do
+      it "updates next_run_at to the sidekiq worker's execution time", :quarantine do
         expect(pipeline_schedule.next_run_at).to eq(cron_worker_next_run_at)
       end
     end