Try fixing Could not load file or assembly 'System.Runtime'

Relates to: #534

src/SyncTrayzor/SyncTrayzor.csproj

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project ToolsVersion="15.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="..\packages\CefSharp.Wpf.49.0.0\build\CefSharp.Wpf.props" Condition="Exists('..\packages\CefSharp.Wpf.49.0.0\build\CefSharp.Wpf.props')" />
   <Import Project="..\packages\CefSharp.Common.49.0.0\build\CefSharp.Common.props" Condition="Exists('..\packages\CefSharp.Common.49.0.0\build\CefSharp.Common.props')" />
   <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />