Added Ruby 4.0 to the CI matrix.

Author: postmodern

.github/workflows/ruby.yml

@@ -12,6 +12,7 @@ jobs:
           - '3.2'
           - '3.3'
           - '3.4'
+          - '4.0'
     name: Ruby ${{ matrix.ruby }}
     steps:
       - uses: actions/checkout@v4