Upgrade to .NET 9.0 and migrate to Duende IdentityServer

Updated all projects to target .NET 9.0, upgrading from .NET Core 3.1.
Replaced IdentityServer4 with Duende IdentityServer due to IdentityServer4's end-of-life.
Updated package references, namespaces, and related code to reflect the migration.

Author: ChaosEngine

src/Hosts/Hosts.CookieAuthentication/Hosts.CookieAuthentication.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>

src/Hosts/Hosts.IdentityServerAuthentication/Controllers/LoginController.cs

@@ -3,10 +3,10 @@
 using System.Linq;
 using System.Security.Claims;
 using System.Threading.Tasks;
+using Duende.IdentityServer;
+using Duende.IdentityServer.Services;
 using Hosts.Shared.InMemory;
 using IdentityManager2;
-using IdentityServer4;
-using IdentityServer4.Services;
 using Microsoft.AspNetCore.Authentication;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;

src/Hosts/Hosts.IdentityServerAuthentication/Hosts.IdentityServerAuthentication.csproj

@@ -1,11 +1,11 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="IdentityServer4" Version="3.1.0" />
+    <PackageReference Include="Duende.IdentityServer" Version="7.3.2" />
   </ItemGroup>
 
   <ItemGroup>

src/Hosts/Hosts.IdentityServerAuthentication/Startup.cs

@@ -2,10 +2,10 @@
 using System.Collections.Generic;
 using System.IdentityModel.Tokens.Jwt;
 using System.Linq;
+using Duende.IdentityServer.Models;
+using Duende.IdentityServer.Test;
 using Hosts.Shared.InMemory;
 using IdentityManager2.Configuration;
-using IdentityServer4.Models;
-using IdentityServer4.Test;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.DependencyInjection;
 

src/Hosts/Hosts.LosthostAuthentication/Hosts.LosthostAuthentication.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>

src/Hosts/Hosts.Shared/Hosts.Shared.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>