Fix macos build re: openssl.

Author: anntzer

Diff for: azure-pipelines.yml

@@ -54,10 +54,8 @@ steps:
       sudo apt install ghostscript inkscape
       ;;
     darwin)
-      # python2 unlinking needed until brew sorts that out.
       # gs<9.50 is needed until matplotlib#15556 (matplotlib<3.2.0rc2).
       brew update >/dev/null &&
-      brew unlink python@2 &&
       brew install cairo pkg-config &&
       PKG_CONFIG_PATH=/usr/local/opt/libffi/lib/pkgconfig tools/build-macos-wheel.sh &&
       brew install https://raw.githubusercontent.com/sashkab/homebrew-core/996730866806cf0dd13a56beac47c664b1408d94/Formula/ghostscript.rb