chore: 升级示例项目为基于 .NET 6.0 的实现

samples/SKIT.FlurlHttpClient.Wechat.TenpayV3.Sample_Net6/Program.cs

@@ -0,0 +1,22 @@
+using System.Text;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.Hosting;
+
+namespace SKIT.FlurlHttpClient.Wechat.TenpayV3.Sample_Net5
+{
+    public class Program
+    {
+        public static void Main(string[] args)
+        {
+            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
+
+            Host.CreateDefaultBuilder(args)
+                .ConfigureWebHostDefaults(builder =>
+                {
+                    builder.UseStartup<Startup>();
+                })
+                .Build()
+                .Run();
+        }
+    }
+}