Actuator missing from package

After installing the package in Unity, I realized that Unity.ML-Agents.Actuator is missing. I then go to the runtime folder and notice that there is no such folder. Is this intended?

The IActuator interface was added after the 1.3.0-preview release. You’ll need to install from the master branch, or wait for 1.4.0-preview, which should be out this week.