`MAINTAINER` in Dockerfile is deprecated

# Description

The `MAINTAINER` in Dockerfile is deprecated according to https://docs.docker.com/reference/dockerfile#maintainer-deprecated.
https://github.com/uyuni-project/uyuni-docs-helper/blob/3a39e52349a64ec8e553631b206abc2288f68bd3/image/Dockerfile#L2

<img width="625" height="399" alt="Image" src="https://github.com/user-attachments/assets/7f94ec5c-4786-4af0-a57c-d46c4fe1c468" />