furrr_options() drops attributes on 'scheduling'

[HenrikBengtsson]

> options <- furrr:::furrr_options(scheduling = structure(2.0, ordering = "random"))
> options$scheduling
[1] 2

It works for chunk_size;

> options <- furrr:::furrr_options(chunk_size = structure(4L, ordering = "random"))
> options$chunk_size
[1] 4
attr(,"ordering")
[1] "random"

[HenrikBengtsson]

It works when the value is an integer;

> options <- furrr:::furrr_options(scheduling = structure(2L, ordering = "random"))
> options$scheduling
[1] 2
attr(,"ordering")
[1] "random"

Note that, contrary to chunk_size, scheduling should take non-integer values.