This will allow to define more properly the dependencies between our debian
packages. Typically some db modules (storage, scheduler, vault, ...) should
require this module as build/test dependencies instead of the plain
python3-swh.core.
Note:
The requirements in the master branch should be reworked (so the pytest-postgresql
is no longer declared on python3-swh.core and such, as currently shown in
the gbp output below) -> D4543
Related to D4376#108929
Related to T2746