Fixed missing reference to resource file in lightweight asset.

Tests/GraphicsTests/RenderPipeline/LightweightPipeline/LightweightPipelineAsset.asset

   m_DefaultShader: {fileID: 4800000, guid: 933532a4fcc9baf4fa0491de14d08ed7, type: 3}
   m_BlitShader: {fileID: 4800000, guid: c17132b1f77d20942aa75f8429c0f8bc, type: 3}
   m_CopyDepthShader: {fileID: 4800000, guid: d6dae50ee9e1bfa4db75f19f99355220, type: 3}
-  m_ResourceAsset: {fileID: 0}
+  m_ResourceAsset: {fileID: 11400000, guid: c8afc0a27fb8c0b4da18151c689a1082, type: 2}