chg: [domain-ip] added the multiple flag back to ports

- as discussed with @righel, if we allow multiple IPs we should also allow multiple ports
- we might revise this in the future if it causes issues, however, then we should also restrict the use of multiple IP addresses

objects/domain-ip/definition.json

@@ -44,6 +44,7 @@
       ],
       "description": "Associated TCP port with the domain",
       "misp-attribute": "port",
+      "multiple": true,
       "ui-priority": 1
     },
     "registration-date": {
@@ -69,5 +70,5 @@
     "hostname"
   ],
   "uuid": "43b3b146-77eb-4931-b4cc-b66c60f28734",
-  "version": 10
+  "version": 11
 }