github ci: remove node 16, add node 20

Author: paulmillr

.github/workflows/nodejs.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        node: [16, 18, 19]
+        node: [18, 20]
         os: [ubuntu-latest]
     steps:
     - uses: actions/checkout@v3