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

[Debian testing autoremoval watch]

ruby-clockwork 1.2.0-3 is marked for autoremoval from testing on 2018-11-27

It is affected by these RC bugs:
912274: ruby-clockwork: ruby-clockwork FTBFS: Mocha::NotInitializedError: Mocha methods cannot be used outside the context of a test