Fix udp_probe

Author: jvazquez-r7

modules/auxiliary/scanner/discovery/udp_probe.rb

@@ -46,6 +46,7 @@ def initialize
     @probes << 'probe_pkt_citrix'
     @probes << 'probe_pkt_pca_st'
     @probes << 'probe_pkt_pca_nq'
+    @probes << 'probe_chargen'
 
   end