Update chef-sugar to fix a conflict in Chef 16+

cookbooks/chef-sugar/spec/unit/recipes/default_spec.rb

@@ -0,0 +1,9 @@
+require 'spec_helper'
+
+describe 'chef-sugar::default' do
+  let(:chef_run) { ChefSpec::SoloRunner.new(platform: 'ubuntu', version: '16.04').converge(described_recipe) }
+
+  it 'converges successfully' do
+    expect { :chef_run }.to_not raise_error
+  end
+end