small change to make object count labeler a team player

com.unity.perception/Runtime/GroundTruth/Labelers/ObjectCountLabeler.cs

         /// <summary>
         /// The <see cref="IdLabelConfig"/> which associates objects with labels.
         /// </summary>
-        public IdLabelConfig labelConfig => m_LabelConfig;
+        public IdLabelConfig labelConfig
+        {
+            get => m_LabelConfig;
+            set => m_LabelConfig = value;
+        }
 
         /// <summary>
         /// Fired when the object counts are computed for a frame.