Land rapid7#8817, fixing @jhart-r7's ruby 2.2 blunder

Author: jhart-r7

modules/auxiliary/scanner/rdp/rdp_scanner.rb

@@ -42,7 +42,7 @@ def rdp?
     sock.put(@probe)
     response = sock.get_once(-1)
     if response
-      if RDP_RE.match?(response)
+      if RDP_RE.match(response)
         # XXX: it might be helpful to decode the response and show what was selected.
         print_good("Identified RDP")
         return true