[gimp-macos-build] Install python3 instead of building it

[Alex Samorukov <asamorukov src gnome org>]

commit e65782ae57977a07071f2ee01c71c27d1bfb1160
Author: Oleksii Samorukov <oleksii_samorukov mckinsey com>
Date:   Sat Oct 26 22:48:39 2019 +0200

    Install python3 instead of building it

 .circleci/config.yml | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/.circleci/config.yml b/.circleci/config.yml
index c516a7a..12b48c3 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -20,6 +20,12 @@ jobs:
               hdiutil mount gfortran-8.2-Mojave.dmg
               sudo installer -pkg /Volumes/gfortran-8.2-Mojave/gfortran-8.2-Mojave/gfortran.pkg -target /
               hdiutil unmount /Volumes/gfortran-8.2-Mojave
+        - run:
+            name: Setup Python3
+            command: |
+              cd ~/
+              curl -L 'https://www.python.org/ftp/python/3.8.0/python-3.8.0-macosx10.9.pkg' > 
python-3.8.0-macosx10.9.pkg
+              sudo installer -pkg python-3.8.0-macosx10.9.pkg -target /
         - run:
             name: Setup 10.9 SDK
             command: |