Update options.py

Author: ilevkivskyi

mypy/options.py

@@ -416,8 +416,6 @@ def __init__(self) -> None:
         # preserving manual tweaks to generated C file)
         self.mypyc_skip_c_generation = False
 
-        self._on_plugins_loaded: Callable[[], None] | None = None
-
     def use_lowercase_names(self) -> bool:
         warnings.warn(
             "options.use_lowercase_names() is deprecated and will be removed in a future version",