Infinite while loop

If the condition in this while loop ever evaluates to ```True```, it will always be ```True```.

current_dt and market_open never change wthin the while loop, which means that since_market_open will never change within the while loop. This means
```python
since_market_open.seconds // 60 <= 14
```
will never evaluate to ```False``` if it is intially ```True```

https://github.com/alpacahq/Momentum-Trading-Example/blob/be4352838eebdd2d124eedd341e31fbae8774f3d/algo.py#L392-L394

I believe it should be:

```python
while since_market_open.seconds // 60 <= 14:
time.sleep(1)
current_dt = datetime.today().astimezone(nyc)
since_market_open = current_dt - market_open
```