bring back strict version dep on base package to -clients

bring back strict version dep on base package to -clients

commit that removed it claimed:

> - removed one more senseless strict internal dep - clients subpackage needs
>   only /etc/ssh directory included in openssh main package since rev. 1.2

but it's not only about /etc/ssh -- when upgrading I'd like to have full
and consistent set of client tools including ssh-key{gen,scan} shipped
in base package