added missing interface method implementation for HDRP

com.unity.perception/Runtime/GroundTruth/RenderPasses/HdrpPasses/GroundTruthPass.cs

         public abstract void SetupMaterialProperties(
             MaterialPropertyBlock mpb, Renderer meshRenderer, Labeling labeling, uint instanceId);
 
+        public abstract void ClearMaterialProperties(
+            MaterialPropertyBlock mpb, Renderer meshRenderer, Labeling labeling, uint instanceId);
+
         protected GroundTruthPass(Camera targetCamera)
         {
             this.targetCamera = targetCamera;