Try to use Ruby 3.4 on "make test"

Author: azumakuniyuki

.github/workflows/rake-test.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        cruby: ["2.4", "3.3"]
+        cruby: ["2.4", "3.3", "3.4"]
     steps:
       - name: Checkout the repository(CRuby)
         uses: actions/checkout@v4