## Bug description

There seems to be an issue with `get_available_timezones_with_offsets`, not sure at what point it broke.

```
Traceback (most recent call last):
    response = view_func(request, *args, **kwargs)
  File "/posthog/posthog/views.py", line 184, in preflight_check
    "available_timezones": get_available_timezones_with_offsets(),
    raise NonExistentTimeError(dt)
```

## Expected behavior
Preflight should work and the timezone list be returned correctly.


## How to reproduce

1. Just check `/_preflight` request

## Environment

- [X] PostHog Cloud
- [ ] self-hosted PostHog, version/commit: _please provide_

## Additional context

Tagging @Twixes as you have more context on this.

#### *Thank you* for your bug report – we love squashing them!

posthog/utils.py
minutes, seconds = divmod(seconds, 60.0)
    hours, minutes = divmod(minutes, 60.0)
    return "{hours}{minutes}{seconds}".format(
        hours="{h} hours ".format(h=int(hours)) if hours > 0 else "",
        minutes="{m} minutes ".format(m=int(minutes)) if minutes > 0 else "",
        seconds="{s} seconds".format(s=int(seconds)) if seconds > 0 or (minutes == 0 and hours == 0) else "",
    ).strip()
def append_data(dates_filled: List, interval=None, math="sum") -> Dict[str, Any]: