Add "unresponsive" to ontology status enum (#2515)

Closes #2255

Co-authored-by: Deepak <[email protected]>

util/schema/registry_schema.json

@@ -7,12 +7,13 @@
     "activity_status": {
       "level": "error",
       "principle": "http://obofoundry.org/principles/fp-016-maintenance.html",
-      "description": "'activity_status' is a required property that must have a value of 'active', 'inactive', or 'orphaned'. Active ontologies have a contact and are currently in development. Orphaned ontologies are still in development, but do not have a contact. Inactive ontologies are no longer in development.",
+      "description": "'activity_status' is a required property that must have a value of 'active', 'inactive', 'orphaned', or 'unresponsive'. Active ontologies have a contact and are currently in development. Orphaned ontologies are still in development, but do not have a contact. Inactive ontologies are no longer in development. Unresponsive ontologies are still being developed, but the maintainers do not respond to discussion on GitHub, email, nor Slack.",
       "type": "string",
       "enum": [
         "active",
         "inactive",
-        "orphaned"
+        "orphaned",
+        "unresponsive"
       ],
       "errors": {
         "activity_status": "${data} is not one of ${schema}."