disable warnings when validating yaml files

Currently, when invoking the planner we see a lot of warnings generated by the schema validation library used
https://github.com/networknt/json-schema-validator


main] WARN schema.JsonMetaSchema - Unknown keyword $defs - you should define your own Meta Schema. If the keyword is irrelevant for validation, just use a NonValidationKeyword
[main] WARN schema.JsonMetaSchema - Unknown keyword additionalItems - you should define your own Meta Schema. If the keyword is irrelevant for validation, just use a NonValidationKeyword


we should turn warnings off at a minimum