## 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
try:
                from ee.models.license import License
            except ImportError:
                pass
            else:
                license = License.objects.first_valid()
                if license is not None and "google_login" in license.available_features:
                    google_login_paid_for = True
            if google_login_paid_for:
                context["google_auth"] = True
            else:
                print_warning(["You have Google login set up, but not the required premium PostHog plan!"])
    
    if os.environ.get("SENTRY_DSN"):
        context["sentry_dsn"] = os.environ["SENTRY_DSN"]
    if settings.DEBUG and not settings.TEST:
        context["debug"] = True
        context["git_rev"] = get_git_commit()
        context["git_branch"] = get_git_branch()
    if settings.SELF_CAPTURE:
        context["self_capture"] = True
        if team:
            context["js_posthog_api_key"] = f"'{team.api_token}'"
            context["js_posthog_host"] = "window.location.origin"
    else:
        context["js_posthog_api_key"] = "'sTMFPsFhdP1Ssg'"
        context["js_posthog_host"] = "'https://app.posthog.com'"
    html = template.render(context, request=request)
    return HttpResponse(html)
def friendly_time(seconds: float):