Add deb822 style sources support

Add support for deb822-style sources files

did my best to keep the previous pre sbuild behaviour

you can see this operate here https://salsa.debian.org/python-team/packages/sphinxcontrib-datatemplates/-/pipelines/937157

see also https://salsa.debian.org/python-team/packages/sphinxcontrib-datatemplates/-/blob/master/debian/salsa-ci.yml?ref_type=heads

Regards

Christian