[3dprinter-general] Bug#976613: Bug#976613: python3-pynest2d: Build for all supported Python versions

[Christoph Berg]

Re: Gregor Riepl
> Please consider building pynest2d for all supported Python interpreters in
> unstable, not just the latest (3.9 at this point).

Right, I had noticed immediately after uploading, and wanted to fix
that once the package get accepted, but I guess I would have forgotten
in the meantime, so thanks for the reminder.

We can probably copy the necessary tweaks from the other cura libs.

Christoph