Zenodo entry uses old ET URL

[Roland Haas]

The current Zenodo entry says:

To find out more, visit http://einsteintoolkit.org

which should be changed to

 To find out more, visit https://www.einsteintoolkit.org 

that is use https transport and add the www part of the hostname for the webserver.

This needs to be manually changed in zupload.py (or similar) when the next ET Zenodo entry is being created.