JsonUtil improvement

[propertius]

Hi @Lambdua, I'm using your library specially for the Assistants API. Since yesterday the added a parallel_tool_calls param, I am getting this error:

Caused by: com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "parallel_tool_calls" (class com.theokanning.openai.assistants.run.Run), not marked as ignorable...

What I did locally as a workaround was to make the JsonUtil internal Mapper a bit more robust, so that unknown properties would not make the parsing fail:

private static class ObjectMapperHolder {
		private static final ObjectMapper MAPPER = new ObjectMapper();
		static {
			MAPPER.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
			MAPPER.setSerializationInclusion(JsonInclude.Include.NON_NULL);
			MAPPER.setPropertyNamingStrategy(PropertyNamingStrategies.LOWER_CAMEL_CASE);
		}
	}

What do you think of this change?

[Lambdua]

I'll check later❤️