Added "Failed" to line 121 of kdc_request.rb

Author: MSadek-r7

lib/rex/proto/kerberos/model/kdc_request.rb

@@ -118,7 +118,7 @@ def decode_asn1(input)
               when 4
                 self.req_body = decode_asn1_req_body(val)
               else
-                raise ::RuntimeError, ' to decode KdcRequest SEQUENCE'
+                raise ::RuntimeError, 'Failed to decode KdcRequest SEQUENCE'
               end
             end
           end