feat: upgrade to Rails 8.1.0 stable and state_machines 0.100.4 (#51)

- Update from Rails 8.1.0.beta to Rails 8.1.0 stable
- Bump state_machines dependency from >= 0.100.1 to >= 0.100.4
- Update Appraisals and gemfile for Rails 8.1.0 stable support

Author: seuros

Appraisals

@@ -10,5 +10,5 @@ appraise 'active_model_8.0' do
 end
 
 appraise 'active_model_8.1' do
-  gem 'activemodel', '~> 8.1.0.beta'
+  gem 'activemodel', '~> 8.1.0'
 end

gemfiles/active_model_8.1.gemfile

@@ -3,7 +3,7 @@
 source "https://rubygems.org"
 
 gem "rubocop"
-gem "activemodel", "~> 8.1.0.beta"
+gem "activemodel", "~> 8.1.0"
 
 platforms :mri do
   gem "debug"

state_machines-activemodel.gemspec

@@ -16,7 +16,7 @@ Gem::Specification.new do |spec|
   spec.test_files    = Dir.glob('test/**/{*_test,test_*}.rb')
   spec.require_paths = ['lib']
   spec.required_ruby_version     = '>= 3.2.0'
-  spec.add_dependency 'state_machines', '>= 0.100.1'
+  spec.add_dependency 'state_machines', '>= 0.100.4'
   spec.add_dependency 'activemodel', '>= 7.2'
 
   spec.add_development_dependency 'bundler', '>= 1.6'