Shopify Product `tags` format is inconsistent between GET and POST

Issue summary

When we access product.tags it returns a string of comma separated tags.
When we save the product, it is required to set the tags to an array of tags.

This means that fetching a product and saving it without touching the tags results in an error :

product_id = XXX
ShopifyAPI::Auth::Session.temp(...) do 
  shopify_product = ShopifyAPI::Product.find(id: product_id)
  # shopify_product.tags = shopify_product.tags.split(', ') # Uncomment this to fix the call
  shopify_product.save!
end

# -> /usr/local/bundle/gems/shopify_api-13.0.0/lib/shopify_api/clients/http_client.rb:71:in `request': {"errors":{"product":"Required parameter missing or invalid"},"error_reference":"If you report this error, please include this id: f610c13a-c4ec-449d-b33f-1204e1eb2c3b."} (ShopifyAPI::Errors::HttpResponseError)

• shopify_api version: 13.0.0
• Ruby version: 3.2.0
• Operating system: MacOs 13.3.1

Expected behavior

The object returned by find or similar fetching methods should be in a state where they can be saved without the user having to map some fields (that he might not even be touching) in a different format.

Actual behavior

If you don't map the tags field from string to array, you can't save the product.

Steps to reproduce the problem

1. Use the given code to reproduce the issue
2. Notice that uncomenting the line makes the error go away

Start by reproducing the issue with ShopifyAPI::Product.find and save!, then inspect the request path referenced at lib/shopify_api/clients/http_client.rb:71 and the product handling around tags. Done means a fetched product can be saved without manually converting tags from a comma-separated string to an array, with the existing reproduction no longer raising the shown error.