Update TestEval test case "list"

TestEval "list" does not work. We should fix or remove.

```
    eval_test.go:169: Eval() got error = failed to evaluate: invalid operation: int(string) (1:14)
         | object.items.isSorted() && object.items.sum() == 6 && object.items.max() == 3 && object.items.indexOf(1) == 0
         | .............^, wantErr false
    --- FAIL: TestEval/list (0.00s)
```