fix compile error

com.unity.ml-agents/Runtime/Inference/BarracudaModelParamLoader.cs

         static FailedCheck CheckRankOneObsShape(
             TensorProxy tensorProxy, ISensor sensor)
         {
-            var shape = sensor.GetObservationShape();
+            var shape = sensor.GetObservationSpec().Shape;
             var dim1Bp = shape[0];
             var dim1T = tensorProxy.Channels;
             var dim2T = tensorProxy.Width;