use matrix.node

.github/workflows/npm.yml

@@ -6,6 +6,9 @@ jobs:
   build:
     name: Build
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node: [ 12, 14, 16 ]
     steps:
       - uses: actions/checkout@v2
       - uses: actions/cache@v2
@@ -18,7 +21,7 @@ jobs:
       - name: Use Node.js 16
         uses: actions/setup-node@v2
         with:
-          node-version: [12, 14, 16]
+          node-version: ${{ matrix.node }}
       - name: Install Dependencies
         run: |
           node --version