loader.svn: Use swh.model objects within the loader
This actually migrates the loader svn to the latest swh.model api change.
This also fixes the current ci build failure [1]
Test Plan
tox
Migrated from D2733 (view on Phabricator)
This actually migrates the loader svn to the latest swh.model api change.
This also fixes the current ci build failure [1]
tox
Migrated from D2733 (view on Phabricator)