net/py-ripe.atlas.sagan: Update to 1.3.1
- Switch to DISTVERSION
- Use pep517 build
- Add pytest tests
- Take maintainership for the time being
ChangeLog: https://github.com/RIPE-NCC/ripe-atlas-sagan/releases/tag/v1.3.1
PR: 277935
Reported by: Marek Zarychta <zarychtam@plan-b.pwste.edu.pl>