Fix policy manifest by changing to

Author: mayorova

gateway/src/apicast/policy/manifest-schema.json

@@ -5,7 +5,7 @@
   "definitions": {
     "schema": {
       "$id": "#/definitions/schema",
-      "$ref": "http://json-schema.org/draft-07/schema#",
+      "$schema": "http://json-schema.org/draft-07/schema#",
       "default": {}
     },
     "version": {