chore(tests): bump the postgres version used in CI

[emilia-grant]

Description

This PR

• Bumps the default version of postgres used when calling make test-database-up from postgres 12 to 16.
  • I chose 16 because our support for 15 ends in 3 months.
• Adds dockerfiles for postgrest 17 and 18
• Fixes tests that broke due to dependence on the order of results returned by the db. Some changes were made in pg 14 that exacerbated this. As far as I can tell, the business logic being tested doesn't seem to care but I'm a bit out of my depth on that.

PCI review checklist

• I have documented a clear reason for, and description of, the change I am making.
• If applicable, I've documented a plan to revert these changes if they require more than reverting the pull request.
• If applicable, I've documented the impact of any changes to security controls.
  Examples of changes to security controls include using new access control methods, adding or removing logging pipelines, etc.