Merge pull request #596 from y-yagi/ci_against_ruby40

CI against Ruby 4.0

Author: rymai

.github/workflows/development.yml

@@ -21,6 +21,7 @@ jobs:
           - 3.2
           - 3.3
           - 3.4
+          - "4.0"
 
         experimental: [false]
         env: [""]