Fix for IPP request tostring(). Fixes #2063

CHANGELOG

@@ -49,6 +49,9 @@ o [Windows] Add support for the new loopback behavior in Npcap 0.9983. This
   Adapter to be installed, which was a source of problems for some users.
   [Daniel Miller]
 
+o [NSE][GH#2063] IPP request object conversion to string was not working
+  correctly [nnposter]
+
 o [NSE][GH#2010] Oracle TNS parser was incorrectly unmarshalling DALC byte
   arrays [nnposter]
 

nselib/ipp.lua

@@ -212,7 +212,7 @@ IPP = {
         data[#data+1] = tostring(group)
       end
       data[#data+1] = string.pack("B", IPP.Attribute.IPP_TAG_END)
-      return data
+      return table.concat(data)
     end,
 
   },