Update test versions

[ricellis]

Checklist

• [x ] Tick to sign-off your agreement to the Developer Certificate of Origin (DCO) 1.1
• [x ] Added tests for code changes or test/build only changes
• [x ] Updated the change log file (CHANGES.md|CHANGELOG.md) or test/build only changes
• [x ] Completed the PR template below:

Description

Set Node.js test versions to 12, 14 and 16

Fixes #467

Approach

Update Jenkinsfile and .travis.yml to use active LTS 16 instead of 17 by changing node for 16.

Schema & API Changes

• "No change"

Security and Privacy

• "No change"

Testing

Changed Node.js test versions.

Monitoring and Logging

• "No change"

[eiri]

lgtm. like the new jenkins matrix naming better too