message: install lab extension
diff: @@ -20,3 +20,7 @@ git clone https://github.com/GLVis/xeus-glvis.git
  pushd xeus-glvis
  make install prefix=$install_dir
  popd
  +
  +# install jupyter-lab extension
  +jupyter labextension install @jupyter-widgets/jupyterlab-manager --no-build
  +jupyter labextension install glvis-jupyter
  