Update github actions workflow to use node@20

Author: watsonarw

.github/workflows/nodejs.yml

@@ -12,7 +12,7 @@ jobs:
     - name: Use Node.js ${{ matrix.node-version }}
       uses: actions/setup-node@v1
       with:
-        node-version: '12.x'
+        node-version: '20.x'
     - run: npm install
     - run: npm run build --if-present
     - run: npm test