**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
"""
    Refreshes a Tableau Workbook/Extract
    .. seealso:: https://tableau.github.io/server-client-python/docs/api-ref#workbooks
    :param workbook_name: The name of the workbook to refresh.
    :type workbook_name: str
    :param site_id: The id of the site where the workbook belongs to.
    :type site_id: Optional[str]
    :param blocking: By default the extract refresh will be blocking means it will wait until it has finished.
    :type blocking: bool
    :param tableau_conn_id: The :ref:`Tableau Connection id <howto/connection:tableau>`
        containing the credentials to authenticate to the Tableau Server.
    :type tableau_conn_id: str
    """
    def __init__(
        self,
        *,
        workbook_name: str,
        site_id: Optional[str] = None,
        blocking: bool = True,
        tableau_conn_id: str = 'tableau_default',
        **kwargs,
    ) -> None:
        super().__init__(**kwargs)
        self.workbook_name = workbook_name
        self.site_id = site_id
        self.blocking = blocking
        self.tableau_conn_id = tableau_conn_id
    def execute(self, context: dict) -> str: