Bug#951842: gringo needs a new upstream, and fixes for python3.8

[Matthias Klose]

Package: src:gringo
Version: 5.3.0-10
Severity: important
Tags: sid bullseye patch
User: debian-python at lists.debian.org
Usertags: python3.8

gringo needs a new upstream, and fixes for python3.8. An example packaging can
be found at
https://launchpad.net/ubuntu/+source/gringo/5.4.0-0ubuntu1

Please note that I didn't address the GCC 8 -> GCC 9 move, which will also be
required for Debian.