Define identity api version in api_versions dict

Change-Id: Id6edb3660d4a50ef68e9091bdf3c2f78fc5d5f4f
diff --git a/metadata/service/server/single.yml b/metadata/service/server/single.yml
index fe119a4..16e78c0 100644
--- a/metadata/service/server/single.yml
+++ b/metadata/service/server/single.yml
@@ -29,10 +29,11 @@
         members:
         - host: ${_param:single_address}
           port: 11211
+      api_versions:
+        identity: ${_param:horizon_identity_version}
       identity:
         engine: keystone
         port: 5000
         host: ${_param:horizon_identity_host}
         encryption: ${_param:horizon_identity_encryption}
-        api_version: ${_param:horizon_identity_version}
         endpoint_type: ${_param:horizon_identity_endpoint_type}