Add the ubi8-python-3.8-jupyter-minimal notebook image to https://github.com/opendatahub-io/jupyter/minimal/ubi8-python-3.8 repository.

Use code from guimou/custom-notebooks repository.

Openshift CI will build and mirror the image to quay.io/opendatahub/notebooks:ubi8-python-3.8-jupyter-minimal repository.