Add Final Target version to prepare for the next Update step

[Natshah]

In update-config.json

  "8.8.10": {
    "from": "8.8.10",
    "to": "8.8.11",
    "final_target_version": "~8.0",
    "composer-project-json-url": "8.8.11"
  },
  "8.8.11": {
    "from": "8.8.11",
    "to": "9.0.1",
    "final_target_version": "~9.0",
    "composer-project-json-url": "9.0.1",
    "packages": {
      "crucial": {
        "drupal/varbase_layout_builder": "~9.0"
      }
    },
    "skip":[
      "vartheme",
      "vartheme_admin",
      "adminimal_admin_toolbar",
      "libraries",
      "libraries_ui",
      "smtp",
      "media_library_theme_reset",
      "color_field",
      "features",
      "l10n_client",
      "tour_builder",
      "webform_analysis",
      "mail_edit"
    ]
  },
  "9.0.0": {
    "from": "9.0.0",
    "to": "9.0.1",
    "final_target_version": "~9.0",
    "composer-project-json-url": "9.0.1"
  },
  "9.0.1": {
    "from": "9.0.1",
    "to": "9.0.1",
    "final_target_version": "~9.0",
    "composer-project-json-url": "9.0.1"
  }

So that at the Final Target version in the composer can be

    "require": {
 ....
        "vardot/varbase": "~9.0",
  .....

    },

Not

"vardot/varbase": "~9.0.1",