breaking: remove node-12 support

[purplecabbage]

Motivation and Context

This pr bumps node support to LTS versions and drops support for 12 which is EOL
Minor version choices are to ensure we get node: namespace supporting versions of node.

How Has This Been Tested?

CI
note that the node-12 tests will not finish since it has been removed in the Github Action CI script

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov]

Codecov Report

Merging #548 (f2af1f4) into master (fb4b9ca) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #548   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           50        50           
  Lines         2598      2598           
  Branches       473       473           
=========================================
  Hits          2598      2598           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update fb4b9ca...f2af1f4. Read the comment docs.