🐛 Fixes post_send_handler deleting channel instead of message

pincer/objects/guild/channel.py

@@ -508,7 +508,7 @@ async def delete(
             headers=remove_none({"X-Audit-Log-Reason": reason})
         )
 
-    async def __post_send_handler(self, message: Message):
+    async def __post_send_handler(self, message: UserMessage):
         """Process a message after it was sent.
 
         Parameters
@@ -519,11 +519,11 @@ async def __post_send_handler(self, message: Message):
 
         if getattr(message, "delete_after", None):
             await sleep(message.delete_after)
-            await self.delete()
+            await message.delete()
 
     def __post_sent(
         self,
-        message: Message
+        message: UserMessage
     ):
         """Ensure the `__post_send_handler` method its future.