Merge pull request #411 from J-Run/patch-1

Update whatweb.rb - fix uninitialized constant error. Add require 'set'

Author: urbanadventurer

lib/whatweb.rb

@@ -31,6 +31,8 @@
 require 'digest/md5'
 require 'openssl' # required for Ruby version ~> 2.4
 require 'pp'
+require 'set'
+
 
 
 # WhatWeb libs