**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).

airflow/providers/tableau/operators/tableau_refresh_workbook.py
"""
        Executes the Tableau Extract Refresh and pushes the job id to xcom.
        :param context: The task context during execution.
        :type context: dict
        :return: the id of the job that executes the extract refresh
        :rtype: str
        """
        with TableauHook(self.site_id, self.tableau_conn_id) as tableau_hook:
            workbook = self._get_workbook_by_name(tableau_hook)
            job_id = self._refresh_workbook(tableau_hook, workbook.id)
            if self.blocking:
                from airflow.providers.tableau.sensors.tableau_job_status import TableauJobStatusSensor
                TableauJobStatusSensor(
                    job_id=job_id,
                    site_id=self.site_id,
                    tableau_conn_id=self.tableau_conn_id,
                    task_id='wait_until_succeeded',
                    dag=None,
                ).execute(context={})
                self.log.info('Workbook %s has been successfully refreshed.', self.workbook_name)
            return job_id
    def _get_workbook_by_name(self, tableau_hook: TableauHook) -> WorkbookItem: