Run on both nodes node versions

.github/workflows/npmjs.yml

@@ -5,16 +5,19 @@ on: [push, pull_request, release]
 jobs:
   build:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node: [ '14', '16' ]
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2
         with:
-          node-version: 14
+          node-version: ${{ matrix.node }}
           registry-url: https://registry.npmjs.org/
       - run: npm ci
       - run: npm test
-      - name: publish
-        if: github.event_name == 'release' && github.event.action == 'created'
+      - name: Run npm publish
+        if: github.event_name == 'release' && github.event.action == 'created' && matrix.node == '16'
         run: npm publish
         env:
           NODE_AUTH_TOKEN: ${{secrets.npm_token}}