use CircleCI workflows to create build matrix. (#234)
use CircleCI workflows to create build matrix. (#234)

Updates the CircleCI config to use the Workflows feature, which allows
testing multiple Go versions.
mosen/micromdm,micromdm/micromdm,mosen/micromdm,groob/micromdm,natewalck/micromdm,groob/micromdm,micromdm/micromdm