I'm encountering an issue when using `redshift_connector` with Okta-based authentication inside my organisation's SageMaker environment.

In `OktaCredentialsProvider.handle_saml_assertion` I receive an error [okta_credentials_provider.py#L158](https://github.com/aws/amazon-redshift-python-driver/blob/fd81061c4dfee9ed3001be039f6b1826d8366302/redshift_connector/plugin/okta_credentials_provider.py#L158) despite receiving a 200 OK and a response of length > 2k.

Upon investigating the logs it seems to be down to a browser or Javascript issue? I've tried on both SageMaker Studio Code Editor and SageMaker Notebook instances and get the same issue.

It's also strange that `OktaCredentialsProvider.okta_authentication` works perfectly and I'm able to retrieve the `okta_session_token`, but the later step fails.

The same identical code works perfectly on my local machine.

I've attached the relevant part of the response below:

```
...

...

Start in redshift_connector/plugin/okta_credentials_provider.py at handle_saml_assertion, especially line 158, and compare the response handling between a local machine and SageMaker. Confirm whether the SageMaker response can be handled compatibly and document a reproducible test or expected behavior for the fix.

索引モデルが issue の本文から書いたものです。