pg-storage: Add missing cur parameter passing
Although, this also pulled a refactoring on the insertion query as the default naive approach ended up with issues on cur already being closed [1]
- [1] Related to swh/meta$712 (which i don't understand ¯_(ツ)_/¯)
Related to !884 (closed)
Test Plan
tox
Migrated from D3420 (view on Phabricator)