fix: remove unnecessary null check for oauth cred exchange

[mconflitti-pbc]

Intent

Support ticket was raised: https://rstudioide.zendesk.com/agent/tickets/115510

There was an extra null check added in the sdk that is unnecessary since the connect endpoint handles this check in the latest version. By adding a default value here, version 0.7.0 breaks when trying to do a credential exchange with an older version of connect < 2025.03.0.

This check is not done in posit-sdk-py so this brings them into parity.

Approach

Removes the null check and default for the requested_token_type. So if the value is not set, a null value is passed through the api which will then determine which the proper default is in both older and newer versions of connect.

Checklist

• Does this change update NEWS.md (referencing the connected issue if necessary)?
• Does this change need documentation? Have you run devtools::document()?

[mconflitti-pbc]

@toph-allen Updated the tests like we did last time since the hashes changed for those two functions. Is this adequate? I am not familiar enough with how to build this and use it locally to verify e2e.

[jonkeane]

Thanks for this!

[mconflitti-pbc]

Verified this fixes the cred exchange call on older version of the connect API.