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 only connection is provided """
        
        conn = mock.Mock()
        del conn.password
        get_connection_mock.return_value = conn
        
        with pytest.raises(AirflowException):
            SlackHook(token=None, slack_conn_id='x')
    @mock.patch('airflow.providers.slack.hooks.slack.SlackHook.get_connection')
    def test_get_token_with_empty_password_slack_conn_id_only(self, get_connection_mock):
        """tests `__get_token` method when only connection is provided """
        
        get_connection_mock.return_value = mock.Mock(password=None)
        
        with pytest.raises(AirflowException):
            SlackHook(token=None, slack_conn_id='x')
    def test_get_token_with_token_and_slack_conn_id(self):
        """tests `__get_token` method when both arguments are provided """
        
        test_token = 'test_token'
        test_conn_id = 'x'
        
        hook = SlackHook(test_token, test_conn_id)
        
        output = hook.token
        expected = test_token
        assert output == expected
    def test_get_token_with_out_token_nor_slack_conn_id(self):