**Apache Airflow version**: 2.0.1

**What happened**:

The operator fails at the last step, after successfully refreshing the workbook with this error:
```
tableauserverclient.server.endpoint.exceptions.ServerResponseError: 

        401002: Unauthorized Access
                Invalid authentication credentials were provided.
```

**What you expected to happen**:
It should not fail, like when we use the username/password authentication method (instead of personal_access_token)

<!-- What do you think went wrong? -->

Tableau server does not allow concurrent connections when using personal_access_token https://github.com/tableau/server-client-python/issues/717
The solution would be redesigning completely the operator to only call the hook once.
My quick fix was to edit this in TableauHook:

```
    def __exit__(self, exc_type: Any, exc_val: Any, exc_tb: Any) -> None:
        pass
```

**How to reproduce it**:

Run this operator TableauRefreshWorkbookOperator using Tableau personal_access_token authentication (token_name, personal_access_token).

tests/providers/tableau/operators/test_tableau_refresh_workbook.py
"""
        Test execute blocking
        """
        mock_tableau_hook.get_all = Mock(return_value=self.mocked_workbooks)
        mock_tableau_hook.return_value.__enter__ = Mock(return_value=mock_tableau_hook)
        operator = TableauRefreshWorkbookOperator(workbook_name='wb_2', **self.kwargs)
        job_id = operator.execute(context={})
        mock_tableau_hook.server.workbooks.refresh.assert_called_once_with(2)
        assert mock_tableau_hook.server.workbooks.refresh.return_value.id == job_id
        mock_tableau_job_status_sensor.assert_called_once_with(
            job_id=job_id,
            site_id=self.kwargs['site_id'],
            tableau_conn_id='tableau_default',
            task_id='wait_until_succeeded',
            dag=None,
        )
    @patch('airflow.providers.tableau.operators.tableau_refresh_workbook.TableauHook')
    def test_execute_missing_workbook(self, mock_tableau_hook):
        """
        Test execute missing workbook
        """
        mock_tableau_hook.get_all = Mock(return_value=self.mocked_workbooks)
        mock_tableau_hook.return_value.__enter__ = Mock(return_value=mock_tableau_hook)
        operator = TableauRefreshWorkbookOperator(workbook_name='test', **self.kwargs)
        with pytest.raises(AirflowException):
            operator.execute({})