Use `workspace:^` for `@smithy` package versions in smithy-rpcv2-cbor

[trivikr]

Is your request related to a problem? Please describe.

The protocol tests start failing when new @smithy/* versions are published.

This happens because smithy-rpcv2-cbor was recently added in #1280, and the script which publishes packages does not update package versions in the protocol test.

It was fixed by manually updating versions in #1394

Describe the solution you'd like

Since it's a monorepo, use workspace:^ for @smithy package versions?

Describe alternatives you've considered

Update npm publish script to update package versions in private clients