Add ruby-head to CI
Add ruby-head to CI

kappezoro/sprockets,Andreis13/sprockets,askl56/sprockets,daniel-rikowski/sprockets,rails/sprockets,sferik/sprockets,basecamp/sprockets,maclover7/sprockets,jcoyne/sprockets,spodlecki/sprockets,dollarshaveclub/sprockets,finnlabs/sprockets,orlando/sprockets,guilleiguaran/sprockets,prusswan/sprockets,bdezonia/sprockets,sideci-sample/sideci-sample-sprockets,schneems/sprockets,prathamesh-sonpatki/sprockets,tricknotes/sprockets,jeremy/sprockets,recursecenter/sprockets,JuanitoFatas/sprockets,byroot/sprockets,eileencodes/sprockets,masarakki/sprockets