refactor(dataset creation): update API methods to return only posts

dto/comment.py

@@ -14,3 +14,14 @@ class Comment:
         self.timestamp = timestamp
         self.reply_to = reply_to
         self.source = source
+
+    def to_dict(self):
+        return {
+            "id": self.id,
+            "post_id": self.post_id,
+            "author": self.author,
+            "content": self.content,
+            "timestamp": self.timestamp,
+            "reply_to": self.reply_to,
+            "source": self.source,
+        }