min/max does not work with dates

[albinkjellin]

Describe the bug
This config results in an error:

order_date:
    tests:
      - min < '2023-01-01'

However its listed in the docs as it should be supported:

To Reproduce
Steps to reproduce the behavior:

1. Create a new test in with min/max for a date in postgres
2. Run soda scan ...
   3 This will be the result:

| Errors occurred!
  |   [test_execution_error] Test "min < '2023-01-01'" failed

Context
Include your scan.yml or warehouse.yml when relevant

OS:
Python Version:
Soda SQL Version:2.1.0b21
Warehouse Type:postgres