community/jupyter-nbconvert: patch for mistune1

This MR fixes #13727 (closed) and fixes #13726 (closed) by adding in py3-mistune as a new aport and patching it so that it is actually named mistune1 to prevent conflicts with the existing py3-mistune package. I patched jupyter-nbconvert to use mistune1 instead of mistune and transitioned it to the new aport. This should unblock !33321 (merged).