Airflow2

[jean-helsinki]

Airflow 2.x support:

• airflow.operators.dummy_operator -> airflow.operators.dummy

• airflow.operators.bash_operator -> airflow.operators.bash

• airflow.sensors.http_sensor -> airflow.providers.http.sensors.http

• tests: fix yaml.load warning

  airflow-declarative/tests/test_good_dags.py:49: YAMLLoadWarning: calling yaml.load() without Loader=... is deprecated, as the default Loader is unsafe. Please read https://msg.pyyaml.org/load for full details.
    schema1 = airflow_declarative.schema.ensure_schema(yaml.load(content))
  

• Test against airflow 2.1

• compat: update for airflow 2

• tests: fix datetimes for airflow 2

    assert yml_dag.start_date == datetime.datetime(2017, 7, 27, 0, 0, 0)
  

  E AssertionError: assert DateTime(2017...mezone('UTC')) == datetime.datet..., 7, 27, 0, 0)
  E -DateTime(2017, 7, 27, 0, 0, 0, tzinfo=Timezone('UTC'))
  E +datetime.datetime(2017, 7, 27, 0, 0)

• Fix broken Operator serialization in airflow 2

  E yaml.representer.RepresenterError: ('cannot represent an object', <class 'airflow.operators.dummy.DummyOperator'>)

• tests coverage: ignore uncovered branches

• Drop airflow 1 support (there is no airflow.operators.dummy module in it)

• Fix deprecation warning about apply_defaults

• Drop compat (py2.7 + airflow 1)

• Drop python 2.7 + airflow 1 support

• Add 2.3.1 patch

• Remove no longer working .travis.yml

• Adopt code for py39, drop py2 references, use poetry for package managment, fix linter hints

• Update trafaret lib, rewrite tox.ini