Un-pin JupyterLab in the binder environment

[choldgraf]

Right now the Binder environment runs JupyterLab ~ .36 or so...that is super out-of-date, and we've gotten some reports in Binder about unexpected behavior with this package. We should un-pin or update the dependency and make sure that it works with the latest jupyterlab

[bollwyvl]

The update pip-based binder has (gah) jupyterlab ~3.0 which should remain accurate for the 3.x line of this extension.