Drop unused ocaml-num dependency
It has not been required since Coq 8.12, cf https://github.com/coq/coq/pull/13007
Due to an influx of spam, we have had to temporarily disable account registrations. Please write an email to accountsupport@archlinux.org, with your desired username, if you want to get access. Sorry for the inconvenience.
It has not been required since Coq 8.12, cf https://github.com/coq/coq/pull/13007