Update src/async.rs

Co-authored-by: Leonardo L. <[email protected]>

Author: praveenperera

src/async.rs

@@ -396,7 +396,7 @@ impl AsyncClient {
         last_seen: Option<Txid>,
     ) -> Result<Vec<Tx>, Error> {
         let path = match last_seen {
-            Some(after_txid) => format!("/address/{address}/txs/chain/{after_txid}"),
+            Some(last_seen) => format!("/address/{address}/txs/chain/{last_seen}"),
             None => format!("/address/{address}/txs"),
         };