feat(process): remove redundant client deletion

Remove redundant client deletion in the `ProcessThon` class to prevent potential issues with the client object being deleted twice. This change ensures that the client is only deleted once when the process is closed, maintaining consistency and avoiding potential errors.

thon/process.py

@@ -173,7 +173,6 @@ class ProcessThon(Data):
             await self.client(UpdateStatusRequest(offline=True))
         with contextlib.suppress(Exception):
             await self.client.disconnect()  # type: ignore  # ty:ignore[unused-ignore-comment]
-        del self.__client
 
     async def __aenter__(self) -> Self | str:
         r = await self.check()