THRIFT-5832 Drop net6 support and add net9 instead
Client: netstd
Patch: Jens Geyer
diff --git a/tutorial/netstd/Server/Server.csproj b/tutorial/netstd/Server/Server.csproj
index 16b72e2..b50b69c 100644
--- a/tutorial/netstd/Server/Server.csproj
+++ b/tutorial/netstd/Server/Server.csproj
@@ -19,12 +19,13 @@
   -->
 
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <LangVersion>latestMajor</LangVersion>
     <AssemblyName>Server</AssemblyName>
     <PackageId>Server</PackageId>
     <OutputType>Exe</OutputType>
     <Version>0.22.0.0</Version>
+    <Nullable>enable</Nullable>
     <GenerateAssemblyConfigurationAttribute>false</GenerateAssemblyConfigurationAttribute>
     <GenerateAssemblyCompanyAttribute>false</GenerateAssemblyCompanyAttribute>
     <GenerateAssemblyProductAttribute>false</GenerateAssemblyProductAttribute>