nest 2.20.0 (new formula)

[tammoippen]

• Have you followed the guidelines for contributing?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing brew install <formula>)?

---

Continuing the migration from in #21561.

Migrating because of: Homebrew/homebrew-science#6331

[chenrui333]

lgtm 💯

[BrewTestBot]

@chenrui333 has triggered a merge.

[laurentperrinet]

by curiosity, why use python@3.8 rather than the standard version available now?

[tammoippen]

@laurentperrinet Homebrew is in transition to python 3.8 (#47274) - at some point it will be the standard version ;). Further all dependencies like numpy, scipy, etc are build already with python@3.8, hence nest / PyNEST need to be build with python@3.8 as well - otherwise we have to vendor (build our own) versions of these dependencies.

[laurentperrinet]

got it thanks. another reason to switch to python@3.8 before the official transition date :-)

thanks, Laurent