Send attachment file via trigger JSON when a comment contains an attachment

Hi there, I'm trying to integrate Zendesk and Service Now, but I'm not being able to send attachments properly.

I've configured a trigger to send a POST HTTP request to a SNow webhook whenever a comment is posted on a ticket. This is working fine.

Now, when trying to send attachments, it is not working. The Snow endpoint "/api/now/attachment/upload" requires a FORM submission instead of plain JSON, returning the error message "Invalid content-type. Supported request media types for this service are: [multipart/form-data]" when I send a payload like this:

{
    "file_name": "name_of_the_file.txt",
    "table_name": "incident",
    "table_sys_id": "..."
}

By using cURL, we can successfully send an attachment using a request like this

curl "https://my-snow-site.service-now.com/api/now/attachment/upload" \
--request POST \
--header "Accept:application/json" \
--user 'admin':'admin' \
--header "Content-Type:multipart/form-data" \
-F 'table_name=incident' -F 'table_sys_id=...' -F 'uploadFile=@<location of the file on file system>'

Is there any way to get a Zendesk trigger to post a form?
Thanks