Make unsupported releases a different error level

Problem/Motivation

An error means something goes wrong. With unsupported release(s) installed, the site is still running, as usual, with nothing broken. It makes no sense to say that it's an error. One possible reason for a project getting unsupported is that the maintainer just does not want to maintain the 'x' branch and focuses on the 'y' branch.

Steps to reproduce

Proposed resolution

Use warning instead? or a new status, such as critical.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet