test with ruby 4

Author: DannyBen

.github/workflows/test.yml

@@ -14,7 +14,7 @@ jobs:
       LC_ALL: en_US.UTF-8 
 
     strategy:
-      matrix: { ruby: ['3.2', '3.3', '3.4'] }
+      matrix: { ruby: ['3.2', '3.3', '3.4', '4.0'] }
 
     steps:
     - name: Checkout code