Update node:8 Docker digest to 6b2c3d7 (#3454)
Update node:8 Docker digest to 6b2c3d7 (#3454)


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