Merge branch 'fix-package-schema-validation' into 'master'

Fix validation of package schema in arrays

See merge request gitlab-org/gitlab!22088

ee/spec/fixtures/api/schemas/public_api/v4/packages/packages.json

 {
   "type": "array",
-  "items": {
-    "type": "object",
-    "properties": {
-      "$ref": "./package.json"
-    }
-  }
+  "items": { "$ref": "./package.json" }
 }