Added MongoDb connection string to config options

Services/HandlePostAction.cs

@@ -14,7 +14,7 @@ namespace mstdnCats.Services
     {
         public static async Task HandleCallbackQuery(CallbackQuery callbackQuery, IDocumentCollection<Post> _db, TelegramBotClient _bot, ILogger<MastodonBot>? logger)
         {
-            var config = configData.fetchData();
+            var config = ConfigData.fetchData();
             
             // Extract media ID from callback query data
             string[] parts = callbackQuery.Data.Split('-');