Prepare for NServiceBus 10 - Set LangVersion (#1779)

* Add LangVersion=preview to Custom.Build.props

* Change LangVersion for VBTestCode.vbproj

The compiler does not support using "preview" for LangVersion in VB projects.

---------

Co-authored-by: Ryan Thomas <[email protected]>

Author: particularbot

src/Custom.Build.props

@@ -3,6 +3,7 @@
   <PropertyGroup>
     <MinVerMinimumMajorMinor>9.0</MinVerMinimumMajorMinor>
     <MinVerAutoIncrement>minor</MinVerAutoIncrement>
+    <LangVersion>preview</LangVersion>
   </PropertyGroup>
 
   <!-- MSBuild tasks require a .NET Framework version to work in Visual Studo, so we have to multi-target. -->

src/VBTestCode/VBTestCode.vbproj

@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>latest</LangVersion>
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>..\NServiceBusTests.snk</AssemblyOriginatorKeyFile>
   </PropertyGroup>