CI: testing on Windows and MacOS too

Author: fisker

.github/workflows/ci.yml

@@ -8,8 +8,15 @@ on:
 
 jobs:
   test:
-    name: Build & Test
-    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - "ubuntu-latest"
+          - "macos-latest"
+          - "windows-latest"
+    runs-on: ${{ matrix.os }}
+    name: Build & Test (${{ matrix.os }})
     steps:
       - uses: actions/checkout@v4