It seems like with the default versioning detection strategy (`docker`),
the version is detected up to the hyphen:

> Renovate tries to follow the most common conventions that are used to tag Docker images.
> In particular, Renovate treats the text after the first hyphen as a type of platform/compatibility indicator.

Perhaps with `semver` would be more appropriate for this image.

More details in: https://docs.renovatebot.com/modules/versioning/