optimize<Issue>: simplify crashreport logic while compiling with .NET 6

Author: love-linger

src/Models/Issue.cs

@@ -1,13 +1,13 @@
 using System;
 using System.Reflection;
+using System.Text;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 
 #if NET6_0_OR_GREATER
 using System.Net.Http;
 #else
 using System.Net;
-using System.Text;
 #endif
 
 namespace SourceGit.Models {
@@ -46,11 +46,9 @@ public static void Create(System.Exception e) {
                     e.StackTrace);
 
 #if NET6_0_OR_GREATER
-                var req = new HttpClient();
-                req.DefaultRequestHeaders.Add("Content-Type", "application/json");
-                req.DefaultRequestHeaders.Add("charset", "UTF-8");
-                req.Timeout = TimeSpan.FromSeconds(1);
-                req.PostAsync("https://gitee.com/api/v5/repos/sourcegit/issues", new StringContent(JsonSerializer.Serialize(issue))).Wait();
+                var content = new StringContent(JsonSerializer.Serialize(issue), Encoding.UTF8, "application/json");
+                var req = new HttpClient() { Timeout = TimeSpan.FromSeconds(1) };
+                req.PostAsync("https://gitee.com/api/v5/repos/sourcegit/issues", content).Wait();
 #else
                 var req = WebRequest.CreateHttp("https://gitee.com/api/v5/repos/sourcegit/issues");
                 req.Method = "POST";