curl --location --request PUT 'https://gitlab.com/api/v3/projects//milestones/'
{
"created_at": "string",
"description": "string",
"due_date": "string",
"id": "string",
"iid": "string",
"project_id": "string",
"start_date": "string",
"state": "string",
"title": "string",
"updated_at": "string"
}