## 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
person = person_factory(
                team_id=self.team.pk, distinct_ids=["blabla", "anonymous_id"], properties={"$some_prop": "some_val"}
            )
            with freeze_time("2020-01-01 00:06:34"):
                event_factory(
                    team=self.team, event="sign up", distinct_id="blabla", properties={"$math_prop": 1},
                )
                event_factory(
                    team=self.team, event="sign up", distinct_id="blabla", properties={"$math_prop": 1},
                )
                event_factory(
                    team=self.team, event="sign up", distinct_id="blabla", properties={"$math_prop": 1},
                )
                event_factory(
                    team=self.team, event="sign up", distinct_id="blabla", properties={"$math_prop": 2},
                )
                event_factory(
                    team=self.team, event="sign up", distinct_id="blabla", properties={"$math_prop": 3},
                )
            with freeze_time("2020-01-02 00:06:34"):
                event_factory(