Uscan with gitlab and user provided tarball

[Ole Streicher <olebole@debian.org>]

Hi,

the upstream of one of my packages recently moved from sourceforge to
Gitlab:

https://gitlab.com/aroffringa/wsclean

He uses git submodules, and this makes the automatically created tarball
incomplete. For my convenience, he created (and hopefully will continue
so) a manual asset, which is linked on the Releases page

https://gitlab.com/aroffringa/wsclean/-/releases/

Unfortunately, the file URL does not have a canonical name, as seen on
the HTML snippet:

<a href="https://gitlab.com/aroffringa/wsclean/-/package_files/15813079/download";
 class="…">
 <svg …>…</svg>
  wsclean-v3.0.tar.bz2
</a>

This HTML is also generated by a script, so not directly downloadable.

Since Gitlab is one of the standard providers, there may be a good
solution to get the correct tarball? Or is there a better way for
upstream to provide a complete tarball than the one chosen here?

Best regards

Ole