Test for all OSes

.github/workflows/test.yaml

@@ -8,13 +8,17 @@ jobs:
   test_default_inputs:
     name: Test with default inputs
 
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
 
     strategy:
       fail-fast: false
       matrix:
         pnpm:
           - 4.11.1
+        os:
+          - ubuntu-latest
+          - macos-latest
+          - windows-latest
 
     steps:
       - uses: actions/checkout@v2