add tests for Ruby 4

Author: kratob

.github/workflows/test.yml

@@ -84,6 +84,8 @@ jobs:
           gemfile: Gemfile.8.0.pg
         - ruby: 3.4.7
           gemfile: Gemfile.8.1.pg
+        - ruby: 4.0.1
+          gemfile: Gemfile.8.1.pg
 
     env:
       BUNDLE_GEMFILE: ${{ matrix.gemfile }}

Gemfile.8.1.pg.lock

@@ -88,4 +88,4 @@ DEPENDENCIES
   rspec_candy
 
 BUNDLED WITH
-   2.7.2
+  4.0.4

spec/assignable_values/active_record_spec.rb

@@ -1,5 +1,4 @@
 require 'spec_helper'
-require 'ostruct'
 
 def save_without_validation(record)
   if ActiveRecord::VERSION::MAJOR < 3