Update type_decorator example to align with python docs

Update type_decorator example to align with python docs

This change updates the `TZDateTime` type decorator to use the timezone awareness checks described in the Python documentation located here:

https://docs.python.org/3/library/datetime.html#determining-if-an-object-is-aware-or-naive

The specific lines state:

> A `datetime` object `d` is aware if both of the following hold:
>
>```python
d.tzinfo is not None
d.tzinfo.utcoffset(d) does not return None
```
>
>Otherwise, `d` is naive.