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

[Debian testing autoremoval watch]

ruby-sidekiq-cron 0.6.3-5 is marked for autoremoval from testing on 2018-10-10

It (build-)depends on packages with these RC bugs:
853256: ruby-sidekiq: Switch form twitter-bootstrap to libjs-bootstrap (v2 to v3)