Fix integer overflow on charges

apps/labrinth/src/models/v3/billing.rs

@@ -161,7 +161,7 @@ pub struct Charge {
     pub id: ChargeId,
     pub user_id: UserId,
     pub price_id: ProductPriceId,
-    pub amount: u64,
+    pub amount: i64,
     pub currency_code: String,
     pub status: ChargeStatus,
     pub due: DateTime<Utc>,
@@ -171,6 +171,9 @@ pub struct Charge {
     pub subscription_id: Option<UserSubscriptionId>,
     pub subscription_interval: Option<PriceDuration>,
     pub platform: PaymentPlatform,
+
+    pub parent_charge_id: Option<ChargeId>,
+    pub net: Option<i64>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]