Upstream on github currently uses submodules for the thirdparty libraries. This
is currently unhandled by uscan:

* https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=902846

One need instead to git clone libjxl and then:

  git submodule update --init -- third_party/highway third_party/lodepng

 -- Mathieu Malaterre <malat@debian.org>  Tue, 14 Dec 2021 10:29:22 +0100
