mismatched simplestream generation

[Dan Bungert]

Today, the simplestream data is generating a mix of new devel series (mantic) and just released series (lunar) data. Presumably after a few builds these would age out.

Example:
    "com.ubuntu.cdimage.daily:ubuntu-server:daily-live:23.10:amd64": {
      "arch": "amd64",
      "image_type": "daily-live",
      "os": "ubuntu-server",
      "release": "mantic",
      "release_codename": "Mantic Minotaur",
      "release_title": "23.10",
      "version": "23.10",
      "versions": {
        "20230415": {
          "items": {
            "iso": {
              "ftype": "iso",
              "path": "ubuntu-server/daily-live/20230415/lunar-live-server-amd64.iso",
              "sha256": "c7cda48494a6d7d9665964388a3fc9c824b3bef0c9ea3818a1be982bc80d346b",
              "size": 2641264640
            },