fix: set correct version label on arch-specific Docker images

[peterpeterparker]

❯ docker image inspect --format '{{json .}}' d707c4d8714a | jq -r '. | {Id: .Id, Digest: .Digest, RepoDigests: .RepoDigests, Labels: .Config.Labels}'

{
  "Id": "sha256:d707c4d8714a452599c77098ec3e4517db22a48ae46a22f700c9789c0448258b",
  "Digest": null,
  "RepoDigests": [
    "junobuild/skylab@sha256:857a3cc249c17761bb3d74df23395f159661d941b9e20d389612027cfae58cdd"
  ],
  "Labels": {
    "homepage": "https://juno.build",
    "maintainer": "David Dal Busco <david.dalbusco@outlook.com>",
    "org.opencontainers.image.created": "2026-02-19T15:55:40.776Z",
    "org.opencontainers.image.description": "📦 Juno Docker images for local dApp development and E2E tests",
    "org.opencontainers.image.licenses": "MIT",
    "org.opencontainers.image.ref.name": "ubuntu",
    "org.opencontainers.image.revision": "81b2b7b3cbf84448a19201b557a7b3877f7eaca5",
    "org.opencontainers.image.source": "https://github.com/junobuild/juno-docker",
    "org.opencontainers.image.title": "juno-docker",
    "org.opencontainers.image.url": "https://github.com/junobuild/juno-docker",
    "org.opencontainers.image.version": "0-arm64",
    "repository": "https://github.com/junobuild/juno-docker"
  }
}

Should not be 0-arm64

Source for the cmd: https://ryandaniels.ca/blog/find-version-tag-latest-docker-image/