[cas] use http client factory

modules/CombotAntiSpam/CombotAntiSpam.cs

@@ -1,6 +1,7 @@
 using Kruzya.TelegramBot.CombotAntiSpam.Combot;
 using Kruzya.TelegramBot.Core;
 using Microsoft.Extensions.DependencyInjection;
+using System;
 
 namespace Kruzya.TelegramBot.CombotAntiSpam;
 
@@ -12,6 +13,9 @@ public class CombotAntiSpam : Module
 
     public override void ConfigureServices(IServiceCollection services)
     {
-        services.AddSingleton<ICombotClient, CombotClient>();
+        services.AddHttpClient<ICombotClient, CombotClient>(c =>
+        {
+            c.BaseAddress = new Uri("https://api.cas.chat/check");
+        });
     }
 }