Fix missing oslo.versionedobjects library option

This ensures the options for oslo.versionedobjects library are
included in the file generated by oslo-config-generator.

Change-Id: I4d113b8ea95b1a5191b5bbd9f1f0dcc36dc9bcfc

tools/config/venus-config-generator.conf

@@ -9,4 +9,5 @@ namespace = oslo.log
 namespace = oslo.service.service
 namespace = oslo.service.periodic_task
 namespace = oslo.service.sslutils
+namespace = oslo.versionedobjects
 namespace = keystonemiddleware.auth_token