Hello,

Slack has released updates to its library and we can start using it for it. 

We especially like one change.

> slack_sdk has no required dependencies. This means aiohttp is no longer automatically resolved.

I've looked through the documentation and it doesn't look like a difficult task, but I think it's still worth testing.
More info: https://slack.dev/python-slack-sdk/v3-migration/index.html#from-slackclient-2-x

Best regards,
Kamil Breguła
tests/providers/slack/hooks/test_slack.py
"""tests `__get_token` method when no arguments are provided """
        with pytest.raises(AirflowException):
            SlackHook(token=None, slack_conn_id=None)
    @mock.patch('airflow.providers.slack.hooks.slack.WebClient')
    def test_call_with_failure(self, slack_client_class_mock):
        slack_client_mock = mock.Mock()
        slack_client_class_mock.return_value = slack_client_mock
        expected_exception = SlackApiError(message='foo', response='bar')
        slack_client_mock.api_call = mock.Mock(side_effect=expected_exception)
        test_token = 'test_token'
        test_slack_conn_id = 'test_slack_conn_id'
        slack_hook = SlackHook(token=test_token, slack_conn_id=test_slack_conn_id)
        test_method = 'test_method'
        test_api_params = {'key1': 'value1', 'key2': 'value2'}
        with pytest.raises(SlackApiError):
            slack_hook.call(test_method, test_api_params)
    @mock.patch('airflow.providers.slack.hooks.slack.WebClient.api_call', autospec=True)
    @mock.patch('airflow.providers.slack.hooks.slack.WebClient')
    def test_api_call(self, mock_slack_client, mock_slack_api_call):
        slack_hook = SlackHook(token='test_token')
        test_api_json = {'channel': 'test_channel'}
        slack_hook.call("chat.postMessage", json=test_api_json)
        mock_slack_api_call.assert_called_once_with(mock_slack_client, "chat.postMessage", json=test_api_json)