minor -- fix type hint for update_rating method

[djcunningham0]

Very minor, but the type hint should be updated for the date parameter in Player.update_rating. It can be pretty much any value that can be sorted (e.g., datetime objects), not just floats or strings.

multielo/multielo/player_tracker.py

Line 48 in 440f792

def update_rating(self, new_rating: float, date: Union[str, float], keep_history: bool = True):