message: Add `new()` for `CreateSubscriptionItems`
diff: @@ -615,6 +615,18 @@ pub struct CreateSubscriptionItems {
  pub tax_rates: Option<Vec<String>>,
  }
  +impl CreateSubscriptionItems {
  + pub fn new(plan: impl AsRef<str>) -> Self {
  + Self {
  + billing_thresholds: Default::default(),
  + metadata: Default::default(),
  + plan: plan.as_ref().to_owned(),
  + quantity: Default::default(),
  + tax_rates: Default::default(),
  + }
  + }
  +}
  +
  #[derive(Clone, Debug, Deserialize, Serialize)]
  pub struct UpdateSubscriptionItems {
  #[serde(skip_serializing_if = "Option::is_none")]
  