Revert to setup-ruby v1.231.0

v1.245.0 is not working with the following issue:

https://github.com/ruby/ruby/actions/runs/15769771616/job/44464179119?pr=13661

```
D:/a/ruby/ruby/src/test/rubygems/mock_gem_ui.rb:83:in 'Gem::MockGemUi#terminate_interaction': Gem::MockGemUi::TermError (Gem::MockGemUi::TermError)
  	D:/a/ruby/ruby/src/lib/rubygems/user_interaction.rb:157:in 'Gem::UserInteraction#terminate_interaction'
  	D:/a/ruby/ruby/src/lib/rubygems/commands/exec_command.rb:175:in 'Gem::Commands::ExecCommand#install'
  	D:/a/ruby/ruby/src/lib/rubygems/commands/exec_command.rb:70:in 'Gem::Commands::ExecCommand#execute'
  	D:/a/ruby/ruby/src/lib/rubygems/command.rb:326:in 'Gem::Command#invoke_with_build_args'
  	D:/a/ruby/ruby/src/lib/rubygems/command.rb:304:in 'Gem::Command#invoke'
  	D:/a/ruby/ruby/src/test/rubygems/test_gem_commands_exec_command.rb:43:in 'TestGemCommandsExecCommand#invoke'
  	D:/a/ruby/ruby/src/test/rubygems/test_gem_commands_exec_command.rb:274:in 'block in TestGemCommandsExecCommand#test_gem_with_platform_and_platform_dependencies'
  	D:/a/ruby/ruby/src/lib/rubygems/user_interaction.rb:46:in 'Gem::DefaultUserInteraction.use_ui'
  	D:/a/ruby/ruby/src/lib/rubygems/user_interaction.rb:69:in 'Gem::DefaultUserInteraction#use_ui'
  	D:/a/ruby/ruby/src/test/rubygems/test_gem_commands_exec_command.rb:272:in 'TestGemCommandsExecCommand#test_gem_with_platform_and_platform_dependencies'
  	D:/a/ruby/ruby/src/tool/lib/test/unit/testcase.rb:202:in 'Test::Unit::TestCase#run_test'
  	D:/a/ruby/ruby/src/tool/lib/test/unit/testcase.rb:170:in 'Test::Unit::TestCase#run'
  	D:/a/ruby/ruby/src/tool/lib/test/unit.rb:1683:in 'block in Test::Unit::Runner#_run_suite'
  	D:/a/ruby/ruby/src/tool/lib/test/unit.rb:1670:in 'Array#map'
  	D:/a/ruby/ruby/src/tool/lib/test/unit.rb:1670:in 'Test::Unit::Runner#_run_suite'
  	D:/a/ruby/ruby/src/tool/lib/test/unit.rb:1374:in 'Test::Unit::ExcludesOption#_run_suite'
  	D:/a/ruby/ruby/src/tool/lib/test/unit/parallel.rb:52:in 'Test::Unit::Worker#_run_suite'
  	D:/a/ruby/ruby/src/tool/lib/test/unit/parallel.rb:24:in 'block in Test::Unit::Worker#_run_suites'
  	D:/a/ruby/ruby/src/tool/lib/test/unit/parallel.rb:23:in 'Array#map'
  	D:/a/ruby/ruby/src/tool/lib/test/unit/parallel.rb:23:in 'Test::Unit::Worker#_run_suites'
  	D:/a/ruby/ruby/src/tool/lib/test/unit/parallel.rb:122:in 'Test::Unit::Worker#run'
  	D:/a/ruby/ruby/src/tool/lib/test/unit/parallel.rb:220:in '<main>'
  running file: D:/a/ruby/ruby/src/test/rubygems/test_gem_commands_exec_command.rb
```

Author: hsbt

.github/workflows/mingw.yml

@@ -66,7 +66,7 @@ jobs:
 
     steps:
       - name: Set up Ruby & MSYS2
-        uses: ruby/setup-ruby@a4effe49ee8ee5b8b5091268c473a4628afb5651 # v1.245.0
+        uses: ruby/setup-ruby@d8d83c3960843afb664e821fed6be52f37da5267 # v1.231.0
         with:
           ruby-version: '3.2'