Improve apertis-pkg-* tools (from apertis-dev-tools) to use python-gitlab instead of relying on urllib

Background

These apertis-pkg-* tools (from apertis-dev-tools) were written long ago and rely on urllib, now we can instead use python-gitlab to simply their code.

Reproducibility

How often the issue is hit when repeating the steps to reproduce and changing nothing?

Put the ✅ in the most appropriate entry:

1. ✅ always
2. often, but not always
3. rarely

Impact of bug

The simplification of the code by python-gitlab will facilitate maintenance.

Outcomes

TBD

Management data

This section is for management only, it should be the last one in the description.

/cc @andrunko @em @Balasubramanian @sudarshan @wlozano

Phabricator link: https://phabricator.apertis.org/T10712