compat: introduce apkg compat level

in order to allow config file changes without disruption in the future.

Fixes: #48
5 jobs for compat in 6 minutes and 18 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #536878
flake8

00:03:54

passed #536881
integration

00:06:18

passed #536879
pylint

00:04:19

passed #536882
self

00:05:36

passed #536880
unit

00:05:11