Changing ownership of a project

How can I change ownership of a project? I would like to start maintaining a project that has been abandoned by its author. I have the original author’s permission to do this.
Is it possible? Or do I have to start a new project?

What project are you going to maintain?
What are its Opendesktop ID and also Source Code Repository?

This one:
and possibly one more later.

It doesn’t have a repository at the moment, I plan to create one at GitLab.

It is currently not possible to transfer, but this feature will come second half this year.
So best is to simply add a new project with same name and ask the original author to deprecate current one and linking to the new one in description.