Docker Hub API changes may break Extension updates (in future)

Docker Hub changed their API (per docker/hub-feedback/issues/2484), which removes the current access pathway to the image architecture information. I believe we will[^1] just need to authenticate to fix this one (which is at least possible in a centralised way, unlike with [core updates](https://github.com/bluerobotics/BlueOS/issues/3489)), but in the meantime we have a broken manifest and the CI system will continue to break it (generating it with no images).

Initially raised in [this forum post](https://discuss.bluerobotics.com/t/cant-install-or-update-any-extensions-on-blueboat/21319).

[^1]: once Docker Hub add the info back to the authenticated version of the API, which they have [already said they'll do](https://github.com/docker/hub-feedback/issues/2484#issuecomment-3175459287)