Allow users to configure the Postgres version being used in Auto DevOps

Problem to solve

I cannot deploy my application using the out of the box Helm chart for Auto DevOps because it uses an older version of Postgres that does not support the features I need for https://gitlab.com/DylanGriffith/gitlab-lightning . I can only use postgres >11 .

Target audience

Further details

Proposal

Ideally an Auto DevOps user should be able to set POSTGRES_VERSION=11.2 and it will install an 11.2 version of Postgres

Documentation

This should be documented with all the other configuration variables in Auto DevOps

What does success look like, and how can we measure that?

I can run my project which needs an 11.2 postgres without customizing the auto-deploy-app helm chart in my project.

Links / references