Update CircleCI build to use Mage
Update CircleCI build to use Mage

Fixes #3969

fedelibre/hugo,mdhender/hugo,fedelibre/hugo,anthonyfok/hugo,anthonyfok/hugo,anthonyfok/hugo,mdhender/hugo,gohugoio/hugo,mdhender/hugo,fedelibre/hugo,fedelibre/hugo,gohugoio/hugo,gohugoio/hugo,mdhender/hugo