Add missing '-> None' to all __init__ methods.

README.md

@@ -29,7 +29,7 @@ __name__ = ...  # type: str
 __package__ = ...  # type: None
 
 class date(object):
-    def __init__(self, year: int, month: int, day: int): ...
+    def __init__(self, year: int, month: int, day: int) -> None: ...
     @classmethod
     def fromtimestamp(cls, timestamp: int or float) -> date: ...
     @classmethod