Fix ZKI NTx for MaxTx

On the Circuits uses the name `nTx` (and on the tests `maxTx`), but
Contracts `maxTx`. On Go we had both variables, but really only used
one, now at Go we use `MaxTx` to refer to the maximum number of
transactions.

common/zk_test.go

@@ -10,7 +10,7 @@ import (
 
 func TestZKInputs(t *testing.T) {
 	chainID := uint16(0)
-	zki := NewZKInputs(chainID, 100, 16, 512, 24, 32, big.NewInt(1))
+	zki := NewZKInputs(chainID, 100, 24, 512, 32, big.NewInt(1))
 	_, err := json.Marshal(zki)
 	require.NoError(t, err)
 	// fmt.Println(string(s))