DateTime field is not serialized in output

If i have a schema with DateTime type field as submit a map to resolve:

```
time: "2021-11-12T12:43:56+00:00"
```

it does not work, as always assumes to have time.Time or *time.Time

This behaviour is not convinent when reading JSON from other sources.

For Boolean "true" works same as Bool, but for some reason conversion from string to DateTime is not supported