update postgres integration tests

[matthewmueller]

Went back through and checked the TODOs to see what can be tested.

[Jolg42]

Thank you @matthewmueller !
I did the translation to MySQL and SQLite

It looks like the tests on dates on SQLite return // PANIC: calledResult::unwrap()on anErr value: ErrorMessage { msg: "Could not parse stored DateTime string: 2018-09-04 00:00:00 (input contains invalid characters)" }

So I will open an issue to see what's happening there 🔥