Remove tag="type" on PaymentRequestMetadata (#4931)

This would conflict with the flattened kind: PaymentRequestMetadataKind
enum, which itself is internally tagged with "type", leading to two
"type" fields being serialized, confusing the deserializer.

Deserialization would fail, be silenced in the stripe webhook and lead
to the incorrect region being assigned to a server.

apps/labrinth/src/routes/internal/billing.rs

@@ -1520,7 +1520,7 @@ pub enum ChargeRequestType {
 }
 
 #[derive(Deserialize, Serialize)]
-#[serde(tag = "type", rename_all = "snake_case")]
+#[serde(rename_all = "snake_case")]
 pub struct PaymentRequestMetadata {
     #[serde(flatten)]
     pub kind: PaymentRequestMetadataKind,