Use Secret's signer fn to get the signer

instead of creating one using the signing key

Author: elizabethengelman

cmd/soroban-cli/src/config/mod.rs

@@ -89,12 +89,10 @@ impl Args {
 
     #[allow(clippy::unused_async)]
     pub async fn sign(&self, tx: Transaction) -> Result<TransactionEnvelope, Error> {
-        let key = self.key_pair()?;
+        let key = &self.source_account.resolve_secret(&self.locator)?;
+        let signer = key.signer(self.hd_path, Print::new(false)).await?;
         let network = &self.get_network()?;
-        let signer = Signer {
-            kind: SignerKind::Local(LocalKey { key }),
-            print: Print::new(false),
-        };
+
         Ok(signer.sign_tx(tx, network).await?)
     }