Fix swh-scheduler debian build

Build is broken [1]. Tests are failing in the unstable chroot.

This needs fixing to allow deployment.

[1] https://jenkins.softwareheritage.org/job/debian/job/packages/job/DSCH/job/gbp-buildpackage/152/console

Migrated from T3666 (view on Phabricator)

Edited Oct 18, 2022 by Antoine R. Dumont