Fix mybinder from having conflicting dependencies

[playermanny2]

Dockerfile currently uses jupyter/minimal-notebook:c54800018c2c to build the extension on top of. This image is over a year old, and causes dependency conflicts.

This should be updated to a later or latest minimal-notebook image in order to have an acceptable jupyterlab version.

Conflicting Dependencies:
JupyterLab              Extension            Package
>=0.15.2-0 <0.16.0-0    >=0.19.1-0 <0.20.0-0 @jupyterlab/application
>=0.15.2-0 <0.16.0-0    >=0.19.1-0 <0.20.0-0 @jupyterlab/apputils
>=0.15.2-0 <0.16.0-0    >=0.19.1-0 <0.20.0-0 @jupyterlab/console
>=1.0.4-0 <2.0.0-0      >=2.1.4-0 <3.0.0-0   @jupyterlab/coreutils
>=0.15.2-0 <0.16.0-0    >=0.19.1-0 <0.20.0-0 @jupyterlab/docmanager
>=0.15.2-0 <0.16.0-0    >=0.19.3-0 <0.20.0-0 @jupyterlab/filebrowser
>=0.15.2-0 <0.16.0-0    >=0.19.2-0 <0.20.0-0 @jupyterlab/notebook
>=0.15.2-0 <0.16.0-0    >=0.19.1-0 <0.20.0-0 @jupyterlab/rendermime

Acceptance Criteria:

1. jupyterlab_voyager mybinder build works properly

[saulshanabrook]

Sounds good to me!

[playermanny2]

Fixed by #67