[DRE-maint] ruby-sidekiq-cron is marked for autoremoval from testing

[Debian testing autoremoval watch]

ruby-sidekiq-cron 1.1.0-3 is marked for autoremoval from testing on 2020-08-04

It (build-)depends on packages with these RC bugs:
963456: ruby-rufus-scheduler: FTBFS: ERROR: Test "ruby2.7" failed: Failure/Error: expect(job.last_work_time).to be < 0.099