Add Ruby 3.4 to CI

Author: kojix2

.github/workflows/test.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu, macos]
-        ruby: [3.2, 3.3]
+        ruby: [3.2, 3.3, 3.4]
 
     steps:
       - uses: actions/checkout@v4