Examples: DirectX12: update Windows SDK version.

(VS2015 doesn't support latest)

examples/example_win32_directx12/example_win32_directx12.vcxproj

@@ -21,7 +21,7 @@
   <PropertyGroup Label="Globals">
     <ProjectGuid>{b4cf9797-519d-4afe-a8f4-5141a6b521d3}</ProjectGuid>
     <RootNamespace>example_win32_directx12</RootNamespace>
-    <WindowsTargetPlatformVersion>10.0.18362.0</WindowsTargetPlatformVersion>
+    <WindowsTargetPlatformVersion>10.0.20348.0</WindowsTargetPlatformVersion>
   </PropertyGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'" Label="Configuration">