Update rails (#251)

* Rails 8.0 support

* Update to Bot API 8.0

.github/workflows/ci.yml

@@ -26,6 +26,8 @@ jobs:
           - gemfiles/rails_51.gemfile
         include:
           # ruby 3.x
+          - ruby: '3.2'
+            gemfile: gemfiles/rails_80.gemfile
           - ruby: '3.2'
             gemfile: gemfiles/rails_72.gemfile
           - ruby: '3.2'