Add an attribute to not break serizliation

com.unity.render-pipelines.high-definition/HDRP/Editor/RenderPipeline/Settings/SerializedRenderPipelineSettings.cs

         public SerializedProperty supportOnlyForward;
         public SerializedProperty supportMotionVectors;
         public SerializedProperty supportStereo;
+        [UnityEngine.Serialization.FormerlySerializedAs("enableUltraQualitySSS")]
+        [UnityEngine.Serialization.FormerlySerializedAs("supportVolumetric")]
         public SerializedProperty supportVolumetrics;
         public SerializedProperty increaseResolutionOfVolumetrics;
         public SerializedProperty supportRuntimeDebugDisplay;