Run ci on multiple machines

Author: inbaltako

.github/workflows/ci.yml

@@ -9,7 +9,10 @@ on:
 
 jobs:
   ci:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-latest, ubuntu-latest, windows-latest]
     steps:
     - name: Notify slack success
       if: success()