travis: Update Node.js versions
travis: Update Node.js versions

Signed-off-by: Anders Kaseorg <087231934ba8fcf78bc142ce37d193b895ac03c4@mit.edu>

nfroidure/ttf2woff2,nfroidure/ttf2woff2,nfroidure/ttf2woff2,nfroidure/ttf2woff2