Run tests on more OS's

Author: arj03

.github/workflows/node.js.yml

@@ -11,10 +11,11 @@ on:
 
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
 
     strategy:
       matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
         node-version: [8.x, 10.x, 12.x, 14.x]
 
     steps: