Deprecation warnings

[virgilp]

I get these sort of warnings when using airflow-dbt:

  /home/virgilp/.local/lib/python3.9/site-packages/airflow_dbt/hooks/dbt_hook.py:7: DeprecationWarning: This module is deprecated. Please use `airflow.hooks.base`.
    from airflow.hooks.base_hook import BaseHook

And indeed, in airflow_dbt/hooks/dbt_hook.py we have the deprecated import even in the latest version of airflow-dbt.

[dinigo]

I think we do this to keep backwards compat with 1.10.x. It can definitely be removed but it will break the library for people using it in "old" airflow deployments. And there's a LOT of people with Airflow 1.10.x both in Google (Composer) or on-prem/self-managed.

The question is if we want to keep supporting those (is it necessary? are they benefitting from the changes in this library?) maybe not, maybe we can remove deprecated code and move on.

We can also set a filter in the "logging" to avoid those appearing, since we already know this is happening :)

We're on version airflow-dbt v0.4.x. Removing it will break the API so it should bring us to v1.x I suppose (based on SEMVER)