fix downgraded PostgreSQL chart version

[crigertg]

Existing Issue

Fixes #367 .

Why do we need this PR?

PostgreSQL version accidentally downgraded in most recent release. This breaks upgrades to existing installations.

Changes proposed in this pull request

• This fixes the accidental downgrade of the PostgreSQL chart (and with it the PostgreSQL version) introduced in the v17.4.0 release.

Contributor Checklist

• Which branch are you merging into?
  • tbh I don't really understand to which branch this change should be merged. master and dev do not reflect the state in release/7.12.x. The release v.17.4.0 which introduced the issue is drafted from release/7.12.x to which I pointed this PR. Please advice if this needs to changed.

Reviewer Checklist

This section is intended for the core maintainers only, to track review progress. Please do not
fill out this section.

• Code reviewed
• Topgun tests run
• Back-port if needed
• Is the correct branch targeted? (master or dev)

[crigertg]

This issue is resolved in the most recent release (v18.0.0)