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

[Debian testing autoremoval watch]

ruby-airbrussh 1.3.1-2 is marked for autoremoval from testing on 2019-03-04

It (build-)depends on packages with these RC bugs:
919818: ruby-net-ssh, src:test-kitchen: ruby-net-ssh breaks test-kitchen autopkgtest