ci: update test workflow to use node 18, 20, and 21 for testing

Author: mrodrig

.github/workflows/automated-tests-workflow.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        node: [16, 18, 19]
+        node: [18, 20, 21]
 
     steps:
       - uses: actions/checkout@v3