Add test against Node.js 16 (#5269)
Add test against Node.js 16 (#5269)

Node.js 16 has been recently released. See also:

- https://medium.com/the-node-js-collection/node-js-16-available-now-7f5099a97e70
- https://nodejs.org/en/blog/release/v16.0.0
- https://github.com/nodejs/Release#release-schedule

According to the release schedule, Node.js 16 will be LTS on **2021-10-26**.
stylelint/stylelint,stylelint/stylelint,stylelint/stylelint,stylelint/stylelint