Follow-up from the update of numpy to 1.16.6 (#29429):

We update

• NumPy to the latest release, 1.18.5
• scipy to latest release, 1.4.1.
  (latest as of 2020-06-05; both versions (and also the upcoming numpy 1.19) support python >= 3.6)

Depends on #29480

CC: @isuruf @dimpase @jdemeyer @embray @slel @vbraun

Component: porting

Author: Matthias Koeppe

Branch/Commit: u/mkoeppe/trac/local_conda_forge_macos_standard__build_error_with_numpy @ 56a6fe1

Reviewer: Isuru Fernando, Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/29425