fixed ruby version backwards compatibility

Author: gene

lib/onelogin/ruby-saml/response.rb

@@ -738,7 +738,7 @@ def validate_subject_confirmation
           next if (attrs.include? "InResponseTo" and attrs['InResponseTo'] != in_response_to) ||
                   (attrs.include? "NotOnOrAfter" and (parse_time(confirmation_data_node, "NotOnOrAfter") + allowed_clock_drift) <= now) ||
                   (attrs.include? "NotBefore" and parse_time(confirmation_data_node, "NotBefore") > (now + allowed_clock_drift)) ||
-                  (attrs.include? "Recipient" and !options[:skip_recipient_check] and attrs['Recipient'] != settings&.assertion_consumer_service_url)
+                  (attrs.include? "Recipient" and !options[:skip_recipient_check] and settings and attrs['Recipient'] != settings.assertion_consumer_service_url)
 
           valid_subject_confirmation = true
           break