Update projects to target .NET 8 and upgrade test dependencies

Migrated all projects from .NET Core 2.0 to .NET 8 for improved performance and support for modern features. Updated test-related dependencies in the UnitTest project to the latest versions to maintain compatibility and ensure better functionality. These changes future-proof the codebase and align it with current .NET standards.

Author: ivandrofly

Algorithms/Algorithms.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>    
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>

DataStructures/DataStructures.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>    
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>

UnitTest/UnitTest.csproj

@@ -1,13 +1,16 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>    
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
     <DotNetCliToolReference Include="dotnet-xunit" Version="2.3.1" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.0.1" />
-    <PackageReference Include="xunit" Version="2.4.1" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
+    <PackageReference Include="xunit" Version="2.9.2" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="3.0.0-pre.49">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
   </ItemGroup>
 
   <ItemGroup>