audit_spec: style fix

Library/Homebrew/test/cask/audit_spec.rb

@@ -124,6 +124,7 @@ describe Cask::Audit, :cask do
 
     describe "required stanzas" do
       let(:only) { ["required_stanzas"] }
+
       %w[version sha256 url name homepage].each do |stanza|
         context "when missing #{stanza}" do
           let(:cask_token) { "missing-#{stanza}" }