could terminado be an extra option ?

Hello, I'm trying to get Jupyter up and running on PyPy-7.3.5 Wndows 64 bit, and I'm stuck because of "pywinpty" not existing for this.

Could terminado be an extra dependancy of 'Notebook' instead of a mandatory one ?

Review Notebook’s dependency declarations and the use of terminado, starting with the installation path for PyPy on Windows. Verify whether making terminado optional still allows supported Notebook functionality to work, and add coverage for the dependency behavior before confirming installation on the reported environment.

Written by the indexing model from the issue text.