Fix format in generated code (spaces in arrays)

The generated code is not complaint with the linter we are using (`solhint`):

For example:
```javascript
  filters: [
    [ Witnet.Types.FILTERS.deviationStandard, 1.5 ],
  ],
})
```

It should be:

```javascript
  filters: [
    [Witnet.Types.FILTERS.deviationStandard, 1.5],
  ],
})
```