Fix type hint issues

Author: mhthies

shc/misc.py

@@ -256,7 +256,7 @@ async def _update(self, value: FadeStep, origin: List[Any]) -> None:
         await self._publish_and_wait(value.apply_to(current_value), origin)
 
 
-class ConvertSubscription(Subscribable[T], Generic[T]):
+class ConvertSubscription(Subscribable[T], Generic[S, T]):
     """
     An adapter, wrapping a subscribable object of value type S and converting it to a subscribable object of value type
     T, using the default converter or a given converter function.