add basic fragmentation support (remembering to cleanup leftover fragments)

Author: tkulin

bellows/ezsp/protocol.py

@@ -53,6 +53,7 @@ def __init__(self, cb_handler: Callable, gateway: Gateway) -> None:
 
         # Cached by `set_extended_timeout` so subsequent calls are a little faster
         self._address_table_size: int | None = None
+        self._cleanup_fragments_periodically()
 
     def _ezsp_frame(self, name: str, *args: Any, **kwargs: Any) -> bytes:
         """Serialize the named frame and data."""