## Is your feature request related to a problem?

There's only 2 files where we use pandas, but pandas is 49MB and numpy is another 86MB, slowing down builds massively.

## Describe the solution you'd like

Replace pandas with a pure SQL/Python solution in
- posthog/queries/trends.py
- posthog/queries/sessions.py

Both of those have equivalent examples in Clickhouse (ee/clickhouse) that don't use Pandas.

## Describe alternatives you've considered

Continue using Pandas and clogging builds

## Additional context



#### *Thank you* for your feature request – we love each and every one!

posthog/queries/test/test_trends.py
team = kwargs.pop("team")
    name = kwargs.pop("name")
    action = Action.objects.create(team=team, name=name)
    ActionStep.objects.create(action=action, event=name)
    action.calculate_events()
    return action
def _create_cohort(**kwargs):
    team = kwargs.pop("team")
    name = kwargs.pop("name")
    groups = kwargs.pop("groups")
    cohort = Cohort.objects.create(team=team, name=name, groups=groups)
    cohort.calculate_people()
    return cohort
class TestDjangoTrends(trend_test_factory(Trends, Event.objects.create, Person.objects.create, _create_action, _create_cohort)):  
    pass