Currently, this pulls the postgresql installation when installing swh.core
which is not something wanted. That bypasses the current production pinning
done in puppet and installs the latest postgresql-13 for example.
That particular dependency should be installed alongside swh modules which
needs the core db pytest-plugin for their tests.
As impacts, i expected current packages needing this to break a bit but those
already declares the pytest-postgresql as test requirements (i probably forgot
to remove them). So, nothing to do, their builds will stay green:
Related to T2746