Update supported shader models for execution tests (#1776)

tools/clang/unittests/HLSL/ExecutionTest.cpp

@@ -454,8 +454,12 @@ public:
   static const D3D_SHADER_MODEL HIGHEST_SHADER_MODEL = D3D_SHADER_MODEL_6_0;
 #elif WDK_NTDDI_VERSION == NTDDI_WIN10_RS3
   static const D3D_SHADER_MODEL HIGHEST_SHADER_MODEL = D3D_SHADER_MODEL_6_1;
-#else
+#elif WDK_NTDDI_VERSION == NTDDI_WIN10_RS4
   static const D3D_SHADER_MODEL HIGHEST_SHADER_MODEL = D3D_SHADER_MODEL_6_2;
+#elif WDK_NTDDI_VERSION == NTDDI_WIN10_RS5
+  static const D3D_SHADER_MODEL HIGHEST_SHADER_MODEL = D3D_SHADER_MODEL_6_3;
+#else
+  static const D3D_SHADER_MODEL HIGHEST_SHADER_MODEL = D3D_SHADER_MODEL_6_4;
 #endif
 
   dxc::DxcDllSupport m_support;