Use double quotes for consistency

Author: rafaelgonzalez

lib/onelogin/ruby-saml/idp_metadata_parser.rb

@@ -2,8 +2,8 @@
 require "uuid"
 require "zlib"
 require "cgi"
-require 'net/http'
-require 'net/https'
+require "net/http"
+require "net/https"
 require "rexml/document"
 require "rexml/xpath"