Land rapid7#6267, update to rspec3

Author: Brent Cook

spec/lib/rex/parser/ini_spec.rb

@@ -1,6 +1,6 @@
 require 'rex/parser/ini'
 
-describe Rex::Parser::Ini do
+RSpec.describe Rex::Parser::Ini do
   let(:ini_contents) { <<EOF
 # global comment
 global settting = blah