Removed unused argument

This was never used, so I don't anticipate much breakage
add in 77912b5 by me, whoops

Author: thomasballinger

curtsies/input.py

@@ -52,7 +52,6 @@ def __init__(
         keynames: str = "curtsies",
         paste_threshold: Optional[int] = events.MAX_KEYPRESS_SIZE + 1,
         sigint_event: bool = False,
-        signint_callback_provider: Optional[Any] = None,
         disable_terminal_start_stop: bool = False,
     ) -> None:
         """Returns an Input instance.