Bug 1613226 - Remove obsolete python@2 from homebrew installation on macOS. r=firefox-build-system-reviewers,rstewart

Differential Revision: https://phabricator.services.mozilla.com/D62286

--HG--
extra : moz-landing-system : lando

python/mozboot/mozboot/osx.py

@@ -347,7 +347,6 @@ class OSXBootstrapper(BaseBootstrapper):
             'gnu-tar',
             'node',
             'python',
-            'python@2',
             'terminal-notifier',
             'watchman',
         ]