[FIX] Fix broken azure_auth test

[jsong468]

This PR addresses the error that was thrown when trying to run the test_get_token_provider_from_default_azure_credential test. This error arose as a result of changes in azure-identity version 1.18 which introduced a get_token_info method which returns an AccessTokenInfo object. The get_token_info method is an alternative method to the previously existing get_token "that improves support for more complex authentication scenarios" and is the default for authentication aside from when the credential object does not have the get_token_info attribute. Thus, the unit tests now mock hasattr for 'get_token_info' arg.

This PR adds unit tests to use both the get_token and get_token_info methods when calling get_token_provider_from_default_azure_credential to connect to an AOAI endpoint.

Also, instances of Mock are changed to MagicMock.

[romanlutz]

Looks good to me. @rdheekonda do you have thoughts on increasing the lower bound on azure-identity?

[nina-msft]

This lambda side-effect solution feels like magic to me 🪄

Clean fix, great work!

[rdheekonda]

Looks good to me. @rdheekonda do you have thoughts on increasing the lower bound on azure-identity?

Thanks for the fix, @jsong468. Could you confirm that this works with latest version azure-identity 1.19.0?