fix: set npm config to read NPM_AUTH_TOKEN

[eunjae-lee]

After multiple tries (since #919 which was a failure), I've found that this line needs to be inside ~/.npmrc in order to read NPM_AUTH_TOKEN environment variable when npm publish is called.

registry.npmjs.org/:_authToken=${NPM_AUTH_TOKEN}

I feel like npm publish never worked before, meaning all of the Ship.js users use yarn?