add more ruby versions to windows test to see if they also fail

Author: akerekes

.github/workflows/unit.yml

@@ -15,7 +15,7 @@ jobs:
     if: ${{ github.repository == 'GoogleCloudPlatform/functions-framework-ruby' }}
     strategy:
       matrix:
-        os: [ubuntu-latest]
+        os: [ubuntu-latest, windows-latest]
         ruby: ['3.1', '3.2', '3.3']
         flags: ["--only --test-unit"]
         include: