simplify build stage

Author: jcs090218

.github/workflows/build.yml

@@ -9,19 +9,14 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
-    
-    strategy:
-      matrix:
-        node-version: [14.x]
-
     steps:
     - name: Checkout repository
       uses: actions/checkout@v2
 
-    - name: Set up Node.js ${{ matrix.node-version }}
+    - name: Set up Node.js
       uses: actions/setup-node@v1
       with:
-        node-version: ${{ matrix.node-version }}
+        node-version: '16'
 
     - name: Set up Yarn
       run: npm install --global yarn && yarn --version