fix: update signAmino method to use messages directly

This change simplifies the code by removing unnecessary mapping of
messages.

packages/stargate/src/signingstargateclient.ts

@@ -405,7 +405,7 @@ export class SigningStargateClient extends StargateClient {
     const signDoc = makeSignDocAmino(msgs, fee, chainId, memo, accountNumber, sequence, timeoutHeight);
     const { signature, signed } = await this.signer.signAmino(signerAddress, signDoc);
     const signedTxBody = {
-      messages: signed.msgs.map((msg) => this.aminoTypes.fromAmino(msg)),
+      messages,
       memo: signed.memo,
       timeoutHeight: timeoutHeight,
     };