Globale namespace custom fields and productSet

Hi. As noted in the reference, global.title_tag and global.description_tag should be included in seoInput, not in metafield, to resolve the issue.

{
  "productSet": {
    "id": "gid://shopify/Product/7851971248188",
    "seo": {
      "title": "The Demo product",
      "description": "The product is a test product"
    },
    "metafields": [
      {
        "key": "brand",
        "namespace": "custome",
        "type": "single_line_text_field",
        "value": "My Brand"
      }
    ]
  },
  "synchronous": true
}

ref. ProductSet and existing global metafield - #4 by AMaL