Update to .NET 8

Author: nicoco007

UnityXRefMap/Properties/launchSettings.json

@@ -1,8 +1,7 @@
 {
   "profiles": {
     "UnityXRefMap": {
-      "commandName": "Project",
-      "commandLineArgs": "2019.3"
+      "commandName": "Project"
     }
   }
 }

UnityXRefMap/UnityXRefMap.csproj

@@ -1,13 +1,13 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="LibGit2Sharp" Version="0.26.2" />
-    <PackageReference Include="YamlDotNet" Version="8.1.2" />
+    <PackageReference Include="LibGit2Sharp" Version="0.31.0" />
+    <PackageReference Include="YamlDotNet" Version="16.2.1" />
   </ItemGroup>
 
   <ItemGroup>