chore: Specify C# version

Reikyo · web-flow · commit 16e7465ede62 · 2025-04-16T16:14:21.000+01:00
diff --git a/Fakes/OpenActive.FakeDatabase.NET/OpenActive.FakeDatabase.NET.csproj b/Fakes/OpenActive.FakeDatabase.NET/OpenActive.FakeDatabase.NET.csproj
@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
+    <LangVersion>8.0</LangVersion>
     <AssemblyName>OpenActive.FakeDatabase.NET</AssemblyName>
     <RootNamespace>OpenActive.FakeDatabase.NET</RootNamespace>
     <PackageId>OpenActive.FakeDatabase.NET</PackageId>
