Add cpio as explicit spec file Requires

[zzndb]

When using osc service disabledrun in official tumbleweed docker image (with obs-service-{obs-scm,tar} installed), I encountered cpio missing error. And I can find cpio as an explicit Depends in debian/control file, so maybe cpio should also be added to spec file explicitly.

[M0ses]

Should be removed from debian/control to make it more consistant.
cpio is not a hard requirement, as tar is not a hard requirement
This all depends on your local setup and your preferences - Recommends should do the job