Run tests weekly [skip ci]

In order to catch breakages caused by supporting dependencies changing (e.g. the recent issues caused by CMake 3.30.0 and Abseil), run the full test suite every Thursday morning. We avoid running on the hour as that is the busiest time for GitHub Actions (see https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#schedule).

.github/workflows/tests.yml

@@ -10,6 +10,8 @@ on:
     branches:
       - main
   pull_request:
+  schedule:
+    - cron: "30 4 * * 4"
 
 env:
   RUBYOPT: "--enable-frozen-string-literal --debug-frozen-string-literal"