don't force yum cookbooks as dependency

On Ubuntu/Debian if there is no 'yum' cookbook knife throws an error during cookbook upload

<pre>ERROR: Cookbook fail2ban depends on cookbook 'yum' version '~> 3.0',
ERROR: which is not currently being uploaded and cannot be found on the server.</pre>

PS> I'm signed CLA, it was trivial but didn't apply to 'Obvious Fix'