Reenable thebe integration #677
Description
It was disabled in #669.
Looks like a work-around like jupyter-book/jupyter-book#1304 (comment) could work by setting the starting folder since all of our .py files (.py files are the ones used for the binder setup see #190) are in the same folder.
In an ideal world it would be fixed in thebe and/or JupyterBook ...