Add a test case to cover an update or upgrade of PostgreSQL on Mac runners

Overview

Similar to the integration:postgres-upgrade on the integration stage, create a new job that tests the same steps but using Mac runners. This will make sure that future rollouts of new PostgreSQL versions are tested on the OS that ~83% of our users use. If the test fails, merging is blocked.

Impacted categories

The following categories relate to this issue:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

Steps to replicate

Introduce a change into the .tool-versions file. This should trigger the new created job alongside the existing integration:postgres-upgrade job.

Proposal

Reuse the logic from the novel stage to install the GDK on Mac runners and then recreate the steps from the integration:postgres-upgrade job to validate the successful update or upgrade of PG.