## Bug description

We've had a user create a funnel with Korean characters and 17 steps, which causes this issue:
![image](https://user-images.githubusercontent.com/1727427/120301818-8c212a00-c2cd-11eb-8b00-7ba242e4a9ab.png)

## Expected behavior

We should send requests to api/insight/funnel using POST instead of GET.

## How to reproduce

1.
2.
3.

## Environment

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

## Additional context



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

posthog/utils.py
try:
        cached_result = cache.get(cache_key)  
        return cached_result
    except Exception:  
        try:
            cache.delete(cache_key)  
        except Exception:
            pass
    return None
def is_anonymous_id(distinct_id: str) -> bool:
    
    return bool(re.match(ANONYMOUS_REGEX, distinct_id))
def mask_email_address(email_address: str) -> str: