fix #24 - document min node version 📝

[bengreenier]

Description

This PR documents minimum required version of node, and also runs our tests targeting that version, the lts version, and the latest version.

Checklist for success

• [x] This change isn't already implemented by a pending pull request
• [x] This change is a child commit of a reasonably recent commit in the master branch
  • Requests need not be a single commit, but should be a linear sequence of commits (i.e. no merge commits in your PR)
• [x] All tests pass locally (see the testing section for more info)
• [x] All New behaviors or major functional changes have tests