re add gemfiles

.github/workflows/ruby.yml

@@ -11,6 +11,18 @@ jobs:
         include:
           - ruby-version: 3.2
           - ruby-version: 3.1
+          - ruby-version: 3.0
+          - ruby-version: 2.7
+          - ruby-version: 3.2
+            gemfile: gemfiles/rails_4.gemfile
+          - ruby-version: 3.2
+            gemfile: gemfiles/rails_5.0.gemfile
+          - ruby-version: 3.2
+            gemfile: gemfiles/rails_5.1.gemfile
+          - ruby-version: 3.2
+            gemfile: gemfiles/rails_5.2.gemfile
+          - ruby-version: 3.2
+            gemfile: gemfiles/rails_6.0.gemfile
     steps:
       - uses: actions/checkout@v2
       - name: Set up Ruby

gemfiles/rails_4.gemfile

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+# This file was generated by Appraisal
+
+source 'http://rubygems.org'
+
+gem 'rails', '~> 4.0'
+
+gemspec path: '../'

gemfiles/rails_5.0.gemfile

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+# This file was generated by Appraisal
+
+source 'http://rubygems.org'
+
+gem 'rails', '~> 5.0.0'
+
+gemspec path: '../'

gemfiles/rails_5.1.gemfile

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+# This file was generated by Appraisal
+
+source 'http://rubygems.org'
+
+gem 'rails', '~> 5.1.0'
+
+gemspec path: '../'

gemfiles/rails_5.2.gemfile

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+# This file was generated by Appraisal
+
+source 'http://rubygems.org'
+
+gem 'rails', '~> 5.2.0'
+
+gemspec path: '../'

gemfiles/rails_6.0.gemfile

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+# This file was generated by Appraisal
+
+source 'http://rubygems.org'
+
+gem 'rails', '~> 6.0.0'
+
+gemspec path: '../'