ChatOption.ResponseFormat doesn't work

[sciutand]

Using

PackageVersion Include="Anthropic" Version="12.3.0"

sample code

public class ManualJob(AnthropicClient client) : Job
{
    public CancellationToken Token { get; set; }

    protected override async Task HandleAsync()
    {
        var chatClient = client.Beta.AsIChatClient("claude-sonnet-4-5-20250929");

        var response = await chatClient.GetResponseAsync(new ChatMessage(ChatRole.User,
                "Tell me a joke and give me a number"),
            new ChatOptions
            {
                ResponseFormat = ChatResponseFormat.ForJsonSchema<ResultDto>()
            },
            Token);

        Console.WriteLine($"{response.Text}");
    }
}

public class ResultDto
{
    public required int Number { get; set; }
    public required string Joke { get; set; }
}

yields

{"type":"error","error":{"type":"invalid_request_error","message":"output_format: This field is deprecated. Use 'output_config.format' instead. See https://platform.claude.com/docs/en/build-with-claude/structured-outputs for more information."},"request_id":"req_011CXnQbWsGEKvt5E5r93b6C"}

The issue is this code still uses the deprecated property