Run test workflow on Windows

Author: codetheweb

.github/workflows/npm-test.yml

@@ -4,10 +4,13 @@ name: NPM Test
 on: ["pull_request"]
 jobs:
   npm_test:
+    strategy:
+      matrix:
+        os: ["ubuntu-20.04", "windows-latest"]
     if: "!contains(github.event.head_commit.message, 'skip ci')"
     name: Run NPM Test
-    runs-on: ubuntu-latest
     timeout-minutes: 30
+    runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout
         uses: actions/checkout@v1