remove extra requirements from doc
remove extra requirements from doc

This was causing the RTD build to fail as ipyleaflet requries ipywidgets<8

jupyter-widgets/ipywidgets,ipython/ipywidgets,ipython/ipywidgets,ipython/ipywidgets,ipython/ipywidgets,jupyter-widgets/ipywidgets,ipython/ipywidgets,jupyter-widgets/ipywidgets,jupyter-widgets/ipywidgets