Php-cs-fixer: CI - Add running CI tests on Mac

[aidantwoods]

• Travis supports testing on Mac: https://docs.travis-ci.com/user/osx-ci-environment/

• Only two tests don't pass: https://github.com/FriendsOfPHP/PHP-CS-Fixer/issues/2846

• These will probably be fixed upstream: https://github.com/sebastianbergmann/phpunit/issues/2697

• No Mac support is 😢

[GrahamCampbell]

Duplicate of https://github.com/FriendsOfPHP/PHP-CS-Fixer/issues/2846. :)

[aidantwoods]

@GrahamCampbell This is a feature request, #2846 is closed because this feature doesn't exist 😉

[SpacePossum]

:+1: for adding this to Travis

[keradus]

PR is welcome @aidantwoods

[aidantwoods]

PR is welcome @aidantwoods

Brb

[keradus]

closed due to merge of #2932

[SpacePossum]

thanks @aidantwoods for raising the issue and the work done, awesome to see we have test for Mac now :)
and thanks @keradus for more work, awesome results :D