Prop displayTimeZone causes inability to type in date field

### I'm Submitting a ...

```
[x] Bug report
[ ] Feature request
[ ] Support request
```

### Steps to Reproduce
Using the following Code Sandbox:
https://codesandbox.io/s/still-cdn-vqoyj?file=/src/App.js

- Click in the react-datetime text field
- Begin typing a valid date/time (e.g. 2021-07-07 00:00:00)

### Expected Results
I'm able to type the date/time and the calendar will highlight the 7th of July

### Actual Results
As soon as I type the first 2, the field re-formats to "0002-01-01 00:00:00" and any further keypresses are lost.

### Minimal Reproduction of the Problem
https://codesandbox.io/s/still-cdn-vqoyj?file=/src/App.js

### Other Information (e.g. stacktraces, related issues, suggestions how to fix)
When the displayTimeZone prop is not set, the value received by the onChange function remains a string until I finish typing the entire dateTime. When displayTimeZone is set, onChange returns a moment as soon as I type a "2", which seems odd. Maybe this is a parsing issue with moment tz and not a react-datetime issue? I'm not well versed enough to know that though.