language: node_js
node_js:
  - "6"
  - "8"
  - "10"

language: node_js
node_js:
  - "8"
  - "10"

Stop testing on Node 6
Stop testing on Node 6

While not ideal (because we still want to support it), this causes
issues with a subdependency. I'd rather have the newest
`devDependencies` than test on all supported Node versions (especially
for such a simple module).
