class RuboCop::Cop::Chef::Modernize::RespondToInMetadata

It is not longer necessary respond_to?(:foo) or defined?(foo) in metadata. This was used to support new metadata methods in Chef 11 and early versions of Chef 12.

@example

### incorrect
chef_version '>= 13' if respond_to?(:chef_version)
chef_version '>= 13' if defined?(chef_version)
chef_version '>= 13' unless defined?(Ridley::Chef::Cookbook::Metadata)
if defined(chef_version)
  chef_version '>= 13'
end

### correct
chef_version '>= 13'