Update GitHub Actions CI

Author: Alkarex

.github/workflows/nodejs.yml

@@ -1,6 +1,10 @@
 name: Node CI
 
-on: [push]
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
 
 jobs:
   build:
@@ -9,14 +13,15 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [10.x, 12.x]
+        node-version: [12.x, 16.x]
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v1
+      uses: actions/setup-node@v2
       with:
         node-version: ${{ matrix.node-version }}
+        cache: 'npm'
     - name: npm install, build, and test
       run: |
         npm ci