Woodwork should not strip timezone information from datetime values upon initialization.

Currently if users have a datetime column in which the input values are timezone aware, the timezone information is removed from the datetime objects after Woodwork initialization. This information should be maintained since downstream process may need to make use of the timezone component of the datetime.

*Current Behavior*
```python
>>> import pandas as pd
>>> import woodwork as ww
>>> df = pd.DataFrame({
... "id": [0, 1, 2],
... "dates": pd.to_datetime(["2020-01-01", "2020-01-02", "2020-01-03"])
... })
>>> df["dates"] = df['dates'].dt.tz_localize("US/Eastern")
>>> df["dates"][0].tz

>>> df.ww.init(logical_types={"dates": "Datetime"})
>>> df["dates"][0].tz is None
True
```

The desired behavior is to have the timezone retained as `` after Woodwork initialization instead of being set to `None`