Update to C# 12 and remove obsolete package references

Author: SadPencil

CnCNet.LauncherStub.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.WindowsDesktop">
   <PropertyGroup>
     <TargetFramework>net471</TargetFramework>
-    <LangVersion>11.0</LangVersion>
+    <LangVersion>12.0</LangVersion>
     <OutputType>WinExe</OutputType>
     <UseWPF>true</UseWPF>
     <Title>CnCNet Launcher</Title>
@@ -25,23 +25,7 @@
   <ItemGroup>
     <Content Include="mainclienticon.ico" />
   </ItemGroup>
-  <ItemGroup>    
-    <Reference Include="System" />
-    <Reference Include="System.Data" />
-    <Reference Include="System.Xml" />
-    <Reference Include="System.Core" />
-    <Reference Include="System.Xml.Linq" />
-    <Reference Include="System.Data.DataSetExtensions" />
-    <Reference Include="System.Xaml"/>
-    <Reference Include="WindowsBase" />
-    <Reference Include="PresentationCore" />
-    <Reference Include="PresentationFramework" />
-  </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.435">
-      <PrivateAssets>all</PrivateAssets>
-      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
-    </PackageReference>
     <PackageReference Include="Microsoft.CSharp" Version="4.7.0" />
   </ItemGroup>
 </Project>