Update to the new `postgresql-client` API (upcoming v4.0.0)

[paluh]

Prelease branch of the lib is here:

https://github.com/rightfold/purescript-postgresql-client/tree/v4.0.0-pre

I'm going to work on this on the branch https://github.com/paluh/purescript-selda/tree/postgresql-client-v4.0.0