Add the option to avoid assigning a default voice

Hi, First of all, I want to thank the author of this wonderful program. This tool is incredibly well thought out and useful. I continue to study it and am already achieving excellent results. And now I would like to draw attention to the fact that in Multi-Speaker, the last assigned participant should continue speaking, not the default role, unless it has been specifically selected. Currently, the program requires assigning a default role if one has not been assigned. But in many cases, it is not needed. Add the option to avoid assigning a default voice. Thank you!