Turn the agent to its left, by a number of degrees.
Mirrors tbp/monty/frameworks/actions/actions.py::TurnLeft. Left is the agent's left, not the world's, which is what makes the same action useful whichever way the agent happens to be facing.
tbp/monty/frameworks/actions/actions.py::TurnLeft
@type t() :: %Monty.Frameworks.Actions.TurnLeft{ agent_id: atom() | String.t(), rotation_degrees: float() }