Run CI unit tests for only last 3 LTS versions of Node

[fershad]

Describe the bug
Currently tests CI unit tests are run for Node versions 14, 16, and 18. However, as some of package dependencies update to using ESM or other modern JS features we might want to consider if we also move our test coverage up to cater for more current versions of Node JS.

Pre the Node docs, the last three LTS releases would be 18, 20, and 22.
https://nodejs.org/en/about/previous-releases

[fershad]

This was done in 4146166