v2: upgrade AWS SDK version

[kmoe]

Closes #383

[jukie]

@kmoe doesn't look like these tests are succeeding against the current v2 branch either. Is anyone working on fixing these or does someone need to take on updating the client config and/or tests?

[nywilken]

@kmoe thanks for open up this PR, and @jukie thanks bubbling up the failures. We are working on getting the tests passing in a separate branch. Once that is working we can rebase and validate that things are working as expected.

[jukie]

Thanks @nywilken! We've already added a workaround internally so no rush but could you offer a rough eta or expectations for cutting a release and getting that pulled upstream to Terraform?