multi: bump btcd version.

The new SignCompact return values had to be adopted across the
code base.

lnrpc/invoicesrpc/addinvoice.go

@@ -587,7 +587,7 @@ func AddInvoice(ctx context.Context, cfg *AddInvoiceConfig,
 
 			return ecdsa.SignCompact(
 				ephemKey, chainhash.HashB(msg), true,
-			)
+			), nil
 		},
 	})
 	if err != nil {

lnrpc/walletrpc/walletkit_server.go

@@ -2647,10 +2647,7 @@ func (w *WalletKit) SignMessageWithAddr(_ context.Context,
 			"fetched from wallet database: %w", err)
 	}
 
-	sigBytes, err := ecdsa.SignCompact(privKey, digest, pubKey.Compressed())
-	if err != nil {
-		return nil, fmt.Errorf("failed to create signature: %w", err)
-	}
+	sigBytes := ecdsa.SignCompact(privKey, digest, pubKey.Compressed())
 
 	// Bitcoin signatures are base64 encoded (being compatible with
 	// bitcoin-core and btcd).