This repository holds a working database.yml for Redmine if using Postgres for your database. The reason I created it was: When I tried running my redmine plugin in CI it wouldn't work, as semaphore had an older version of MySQL. That caused some issue with id's.
You can simply clone this database.yml into the config folder and use it out of the box.
This saved me a lot of nerves, I hope it does the same for you!