fix z fighting issue

Author: ritijain

Assets/MixedRealityToolkit.Examples/Demos/HandTracking/Prefabs/TestCanvas.prefab

@@ -474,7 +474,7 @@ RectTransform:
   m_PrefabAsset: {fileID: 0}
   m_GameObject: {fileID: 1161460687503986}
   m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
-  m_LocalPosition: {x: 0, y: 0, z: 0}
+  m_LocalPosition: {x: 0, y: 0, z: -0.001}
   m_LocalScale: {x: 1, y: 1, z: 1}
   m_Children:
   - {fileID: 224822620892401644}