Call `get_objstorage` without explicit `args` argument
This explicit argument was deprecated in swh.objstorage 0.2.2.
Test Plan
tox shows no more deprecation warnings
Migrated from D4215 (view on Phabricator)
This explicit argument was deprecated in swh.objstorage 0.2.2.
tox shows no more deprecation warnings
Migrated from D4215 (view on Phabricator)