Fix extra values

Models/Post.cs

@@ -1,9 +1,12 @@
 using System.Text.Json.Serialization;
+using MongoDB.Bson;
+using MongoDB.Bson.Serialization.Attributes;
 using Telegram.Bot.Types;
 
 
 namespace mstdnCats.Models
 {
+    [BsonIgnoreExtraElements]
     public class Post
     {
         [JsonPropertyName("id")]

Services/HandleDbBackup.cs

@@ -14,7 +14,7 @@ public class HandleDbBackup
     {
         logger?.LogInformation("Backup requested");
         
-        // Retrieve all posts from DB
+        // Retrieve all posts from DB (Exclude _id field from mongoDB since it is not needed nor implemented in Post model)
         var posts = _db.AsQueryable().ToList();
         // Retrieve all existing posts in backup DB
         var existingPosts = _bkDb.AsQueryable().ToList();