chg: [shadowserver-malware-url-report] sane default added for severity

Ref: https://github.com/The-Shadowserver-Foundation/report_schema/blob/main/severity.md

Author: adulau

objects/shadowserver-malware-url-report/definition.json

@@ -71,6 +71,13 @@
       "description": "Severity of the report",
       "disable_correlation": true,
       "misp-attribute": "text",
+      "sane_default": [
+        "critical",
+        "high",
+        "medium",
+        "low",
+        "info"
+      ],
       "ui-priority": 0
     },
     "sha256": {
@@ -111,5 +118,5 @@
     "url"
   ],
   "uuid": "0211496c-dbcf-465b-a147-3d965da016cc",
-  "version": 4
+  "version": 5
 }