Update Split

curl --request PUT \
  --url https://server26-dot-royalti-project.uc.r.appspot.com/split/{id} \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "share": 123,
  "userId": "<string>"
}'

{
  "message": "Split updated successfully"
}