ToolChoice not accepting "none"

[toshiakit]

Currently you cannot select "none" for ToolChoice

function toolChoice = convertToolChoice(this, toolChoice)
    % if toolChoice is empty
    if isempty(toolChoice)
        % if Tools is not empty, the default is 'auto'.
        if ~isempty(this.Tools) 
            toolChoice = "auto";
        end
    elseif ToolChoice ~= "auto"
        % if toolChoice is not empty, then it must be in the format
        % {"type": "function", "function": {"name": "my_function"}}
        toolChoice = struct("type","function","function",struct("name",toolChoice));
    end

end

We should fix this

function toolChoice = convertToolChoice(this, toolChoice)
    % if toolChoice is empty
    if isempty(toolChoice)
        % if Tools is not empty, the default is 'auto'.
        if ~isempty(this.Tools) 
            toolChoice = "auto";
        end
    elseif ~ismember(ToolChoice,["auto","none"])
        % if toolChoice is not empty, then it must be "none" or in the format
        % {"type": "function", "function": {"name": "my_function"}}
        toolChoice = struct("type","function","function",struct("name",toolChoice));
    end

end