Add support for emoji_added message type

discord/message.py

@@ -2865,6 +2865,9 @@ class Message(PartialMessage, Hashable):
             )
             return f"{self.author.display_name}'s poll {poll_title.value} has closed."  # type: ignore
 
+        if self.type is MessageType.emoji_added:
+            return f'{self.author.name} added a new emoji, {self.content}'
+
         # Fallback for unknown message types
         return ''