[c#] enable the latest language features.

Author: Jing KE

Directory.Build.targets

@@ -0,0 +1,13 @@
+<!--
+~ INTRO:
+~ Directory.Build.targets is imported from Microsoft.Common.targets after importing .targets files from NuGet
+~ packages. So, it can override properties and targets defined in most of the build logic, but sometimes you may need
+~ to customize the project file after the final import.
+~ See: https://docs.microsoft.com/en-us/visualstudio/msbuild/customize-your-build#import-order
+-->
+<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <!-- Enable the latest programming language features. -->
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+</Project>