handle jupyer request messages

I just noticed this while updating cocalc to have the latest Colab image:

<img width="1043" height="579" alt="Image" src="https://github.com/user-attachments/assets/c333a861-5f27-4362-afaf-31348cab6cd9" />

Their python jupyter kernel is outputting some messages like `{"request":{"delayMillis":500}}` that aren't handled by cocalc.