How do we make UPM show that there is a newer package for a package installed via git URL?

Hello.

We have a custom package in git. We install it via Unity Package Manager (UPM) but the project always shows a green tick even when a new version has been released (see picture)

We have already published version 1.0.0-preview.2 but the Package Manager still shows preview.1 as the latest, and it won't display the 'update' button.

Is there a way to make it realise that there is a new version in our git repo?