add langversion to 7.2

src/Microsoft.ApplicationInsights.AspNetCore/Microsoft.ApplicationInsights.AspNetCore.csproj

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <AssemblyName>Microsoft.ApplicationInsights.AspNetCore</AssemblyName>
     <VersionPrefix>2.8.0-beta3</VersionPrefix>
-    
+    <LangVersion>7.2</LangVersion>
     <TargetFrameworks>net451;net46;netstandard1.6;netstandard2.0</TargetFrameworks>
     <TargetFrameworks Condition=" '$(OS)' != 'Windows_NT' ">netstandard1.6;netstandard2.0</TargetFrameworks>