Merge branch '11120-autodevops-test-postgres-version' into 'master'

Added POSTGRES_VERSION variable to Auto DevOps Test stage

Closes #11120

See merge request gitlab-org/gitlab!22884

changelogs/unreleased/11120-autodevops-test-postgres-version.yml

+---
+title: Use POSTGRES_VERSION variable in Auto DevOps Test stage
+merge_request:
+author: Serban Marti
+type: fixed

lib/gitlab/ci/templates/Jobs/Test.gitlab-ci.yml

 test:
   services:
-    - postgres:latest
+    - "postgres:${POSTGRES_VERSION}"
   variables:
     POSTGRES_DB: test
   stage: test