refactor: 💡 Build with LTS, test with Matrix

[tsamaya]

Linting, unit testing and building with a matrix of node runtimes does not make sense.
We need one runtime to lint, test, build and then a Matrix of runtimes to check against the live API.
The PR does that.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (ab3ffe6) to head (458ed97).
⚠️ Report is 10 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #609   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            6         6           
  Lines           72        72           
  Branches        15        15           
=========================================
  Hits            72        72           

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