## 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
date = date - relativedelta(day=1)
        if match.group("position") == "End":
            date = date - relativedelta(day=31)
    elif match.group("type") == "y":
        if match.group("number"):
            date = date - relativedelta(years=int(match.group("number")))
        if match.group("position") == "Start":
            date = date - relativedelta(month=1, day=1)
        if match.group("position") == "End":
            date = date - relativedelta(month=12, day=31)
    return date.replace(hour=0, minute=0, second=0, microsecond=0)
def request_to_date_query(filters: Dict[str, Any], exact: Optional[bool]) -> Dict[str, datetime.datetime]:
    if filters.get("date_from"):
        date_from: Optional[datetime.datetime] = relative_date_parse(filters["date_from"])
        if filters["date_from"] == "all":
            date_from = None
    else:
        date_from = datetime.datetime.today() - relativedelta(days=7)
        date_from = date_from.replace(hour=0, minute=0, second=0, microsecond=0)
    date_to = None
    if filters.get("date_to"):
        date_to = relative_date_parse(filters["date_to"])
    resp = {}
    if date_from:
        resp["timestamp__gte"] = date_from.replace(tzinfo=pytz.UTC)
    if date_to:
        days = 1 if not exact else 0
        resp["timestamp__lte"] = (date_to + relativedelta(days=days)).replace(tzinfo=pytz.UTC)
    return resp
def get_git_branch() -> Optional[str]: