Use the 'correct' windows platform version (#7338)

src/SignalR/clients/cpp/src/signalrclient/Build/VS/signalrclient.vcxproj

@@ -12,7 +12,7 @@
     <OutDir>$(OutDir)lib\</OutDir>
     <IntDir>$(Configuration)\lib\</IntDir>
     <ConfigurationType>StaticLibrary</ConfigurationType>
-    <WindowsTargetPlatformVersion>10.0.17763.0</WindowsTargetPlatformVersion>
+    <WindowsTargetPlatformVersion>10.0.17134.0</WindowsTargetPlatformVersion>
   </PropertyGroup>
   <Import Project="..\..\..\..\Build\Config.Definitions.props" />
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />