chore: switch Reference to using an actual reference

crates/delta/src/routes/servers/server_ack.rs

@@ -12,7 +12,7 @@ use rocket_empty::EmptyResponse;
 /// Mark all channels in a server as read.
 #[openapi(tag = "Server Information")]
 #[put("/<target>/ack")]
-pub async fn ack(db: &State<Database>, user: User, target: Reference) -> Result<EmptyResponse> {
+pub async fn ack(db: &State<Database>, user: User, target: Reference<'_>) -> Result<EmptyResponse> {
     if user.bot.is_some() {
         return Err(create_error!(IsBot));
     }