ci: only test macOS/Windows on schedule and manual dispatch

Author: pengzhendong

.github/workflows/unittest.yml

@@ -2,6 +2,8 @@ name: UnitTest
 
 on:
   workflow_dispatch:
+  schedule:
+    - cron: '0 3 * * 1'
   pull_request:
     paths:
       - '**.py'
@@ -15,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: ${{ github.event_name == 'pull_request' && fromJSON('["ubuntu-latest"]') || fromJSON('["ubuntu-latest", "macos-latest", "windows-latest"]') }}
         python-version: ['3.9']
     steps:
       - uses: actions/checkout@v4