set jest to only use one worker on circleCI
set jest to only use one worker on circleCI

nteract/nteract,nteract/composition,jdfreder/nteract,jdfreder/nteract,nteract/composition,jdfreder/nteract,nteract/composition,nteract/nteract,nteract/nteract,rgbkrk/nteract,rgbkrk/nteract,jdfreder/nteract,rgbkrk/nteract,rgbkrk/nteract,nteract/nteract,rgbkrk/nteract,nteract/nteract