## Bug description

Deprecation warning due to invalid escape sequences in Python 3.8 . 

```
posthog/models/team.py:47:46: W605 invalid escape sequence '\w'
posthog/models/filters/test/test_filter.py:131:74: W605 invalid escape sequence '\.'
posthog/models/filters/test/test_filter.py:135:78: W605 invalid escape sequence '\.'
posthog/migrations/0132_team_test_account_filters.py:51:46: W605 invalid escape sequence '\w'
ee/clickhouse/views/element.py:47:48: W605 invalid escape sequence '\.'
ee/clickhouse/views/element.py:50:69: W605 invalid escape sequence '\.'
```

This is little more important since Python emits deprecation warning during compile time for these

## Expected behavior

This can be fixed with pyupgrade : https://github.com/asottile/pyupgrade#invalid-escape-sequences . Appropriate rule can be added to flake8 so that this caught.

## How to reproduce


```
find posthog -iname '*py' | xargs -P4 -I{} python3.8 -Wall -m py_compile {}     
posthog/models/team.py:47: DeprecationWarning: invalid escape sequence \w
  example_email = re.search("@[\w.]+", example_emails[0])
posthog/models/filters/test/test_filter.py:131: DeprecationWarning: invalid escape sequence \.
  filter = Filter(data={"properties": {"$current_url__regex": "\.com$"}})
posthog/models/filters/test/test_filter.py:135: DeprecationWarning: invalid escape sequence \.
  filter = Filter(data={"properties": {"$current_url__not_regex": "\.eee$"}})
posthog/migrations/0132_team_test_account_filters.py:51: DeprecationWarning: invalid escape sequence \w
  example_email = re.search("@[\w.]+", example_emails[0])
```

## Environment

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

## Additional context



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

posthog/models/team.py
kwargs["test_account_filters"] = self.set_test_account_filters(kwargs.get("organization"))
        team = Team.objects.create(**kwargs)
        
        
        if default_dashboards:
            dashboard = Dashboard.objects.create(name="My App Dashboard", pinned=True, team=team)
            create_dashboard_from_template("DEFAULT_APP", dashboard)
        return team
    def create(self, *args, **kwargs) -> "Team":
        if kwargs.get("organization") is None and kwargs.get("organization_id") is None:
            raise ValueError("Creating organization-less projects is prohibited")
        return super().create(*args, **kwargs)
    def get_team_from_token(self, token: Optional[str]) -> Optional["Team"]:
        if not token:
            return None
        try:
            return Team.objects.defer(*DEPRECATED_ATTRS).get(api_token=token)
        except Team.DoesNotExist:
            return None
def get_default_data_attributes() -> Any:
    return ["data-attr"]
class Team(UUIDClassicModel):