ci: run tests on Windows and macOS (#15)

Author: amezin

.github/workflows/test.yml

@@ -8,7 +8,14 @@ on:
 
 jobs:
   test:
-    runs-on: "ubuntu-latest"
+    strategy:
+      fail-fast: false
+      matrix:
+        runs-on:
+          - "ubuntu-latest"
+          - "windows-latest"
+          - "macos-latest"
+    runs-on: "${{ matrix.runs-on }}"
     steps:
       - uses: "actions/[email protected]"