Test with Ruby 4.0 on CI [skip ci]

Author: ankane

.github/workflows/build.yml

@@ -6,7 +6,7 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - ruby: 3.4
+          - ruby: "4.0"
             gemfile: Gemfile
             elasticsearch: 9
           - ruby: 3.3