Adding node 20.x to unit test environments

Author: ezolenko

.github/workflows/nodejs.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        node-version: [12.x, 14.x, 16.x, 18.x]
+        node-version: [12.x, 14.x, 16.x, 18.x, 20.x]
         os: [ubuntu-latest, windows-latest, macOS-latest]
 
     steps: