Test with Ruby 4.0 on CI

Author: ankane

.github/workflows/build.yml

@@ -7,7 +7,7 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - ruby: 3.4
+          - ruby: "4.0"
             gemfile: Gemfile
           - ruby: 3.4
             gemfile: gemfiles/activerecord80.gemfile