python3-arcus only builds for python 3.8 despite pybuild

[Gregor Riepl <onitake@gmail.com>]

Hi,

arcus is having some build/test issues related to Python 3.7 and 3.8:
https://salsa.debian.org/3dprinting-team/libarcus/-/jobs/512109

In the built artifact, there is only a SIP module for python3.8, but
autopkgtest only only installs python3.7:
https://salsa.debian.org/3dprinting-team/libarcus/-/jobs/512103/artifacts/file/debian/output/python3-arcus_4.4.1-1+salsaci_amd64.deb

arcus is built like this:
        dh $@ --buildsystem=pybuild --with python3 --with sip3

Does someone have an idea why pybuild doesn't produce python3.7 and 3.8
modules, and why autopkgtest only installs python3.7 for the test dependency?

Regards,
Gregor