Tableau Workbook refresh getting InvalidRestApiVersion error for my 'api_version': '2.6',

My tableau API version is 2.6

My Python code:

from tableau_api_lib import TableauServerConnection

from tableau_api_lib.utils.querying import get_views_dataframe, get_view_data_dataframe, get_workbooks_dataframe,get_datasources_dataframe

tableau_server_config = {

    'my_env': {

        'server': 'https://myserver.com',

        'api_version': '2.6',

        'username': 'username',

        'password': 'password,

        'site_name': 'ABC',

        'site_url': '',

        'cache_buster': '',

        'temp_dir': ''

    }

}

conn = TableauServerConnection(config_json=tableau_server_config, env='my_env')

conn.sign_in()

#print(conn.query_sites().json()) 

workbooks_df = get_workbooks_dataframe(conn)

#print(workbooks_df[['name', 'id']])

wb_response = conn.update_workbook_now('abcd-efgh-ijkl-mnop-qrst')

while executing i am getting error as:

InvalidRestApiVersion: 

    The REST API endpoint referenced in function 'update_workbook_now' requires a minimum API version of 2.8.

    The API version you are using is 2.6, which pre-dates the endpoint referenced.

    Please visit Tableau's REST API reference to identify the methods relevant for your legacy API version.