ci: add macOS and Windows to test matrix

Author: pengzhendong

.github/workflows/unittest.yml

@@ -9,9 +9,10 @@ on:
 
 jobs:
   unit-test:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
       matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
         python-version: [3.9]
     steps:
       - uses: actions/checkout@v4