`when_any` should specify type for input `tasks`

[larohra]

when_any should also specify the generic type for the tasks similar to when_all

def when_all(tasks: list[Task[T]]) -> WhenAllTask[T]:
    """Returns a task that completes when all of the provided tasks complete or when one of the tasks fail."""
    return WhenAllTask(tasks)


def when_any(tasks: list[Task]) -> WhenAnyTask:
    """Returns a task that completes when any of the provided tasks complete or fail."""
    return WhenAnyTask(tasks)

[andystaples]

There is a type safety improvement here but I don't think it's quite what this PR proposes, since WhenAllTask returns the result of the input tasks, but WhenAnyTask returns the task that completes first, from which you need to extract the result, to allow comparisons to determine which tasks are remaining and still need to complete.
I'll take a look and fix up the type hints anyway as part of #92