Renovate not updating postgres package

Summary

We discovered in #155 (closed) that renovate is not proposing updates to the postgres chart or image, allowing it to fall several major versions behind.

Steps to reproduce

Attempt to perform renovate on any version of the mattermost chart which references anything other than the latest available bitnami postgres chart or ironbank version and observe it failing to propose an update.

What is the current behavior?

Renovate does not detect or propose the updates to postgresql

What is the expected behavior?

Renovate detects and proposes a change to postgresql

Relevant logs and/or screenshots

No specific logs, you can inspect previous renovate tickets on any mattermost renovate to see that postgres is being ignored.

Possible fixes

This may be due to the regex in renovate.json, there does not appear to be an entry for the postgresql image or chart.

/cc {put CODEOWNERs @githandles here}