Update appraisals

- add one for each Rails minor version
- remove Rails 4, it does not support Bundler 2 which makes testing painful

.travis.yml

@@ -1,13 +1,17 @@
 language: ruby
 cache: bundler
 rvm:
-  - 2.6.5
-  - 2.5.5
-  - 2.4.5
-  - 2.3.8
-  - jruby-9.1.16.0
+  - 2.7
+  - 2.6
+  - 2.5
+  - 2.4
+  - 2.3
+  - jruby
 gemfile:
-  - gemfiles/rails5.gemfile
+  - gemfiles/rails5.0.gemfile
+  - gemfiles/rails5.1.gemfile
+  - gemfiles/rails5.2.gemfile
+  - gemfiles/rails6.0.gemfile
 matrix:
   fast_finish: true
 env:

Appraisals

@@ -1,7 +1,12 @@
-appraise 'rails4' do
-  gem 'rails', '>= 4.0.0', '< 5'
+appraise 'rails5.0' do
+  gem 'rails', '~> 5.0.0'
 end
-
-appraise 'rails5' do
-  gem 'rails', '5.0.0.beta2'
+appraise 'rails5.1' do
+  gem 'rails', '~> 5.1.0'
+end
+appraise 'rails5.2' do
+  gem 'rails', '~> 5.2.0'
+end
+appraise 'rails6.0' do
+  gem 'rails', '~> 6.0.0'
 end

gemfiles/rails5.0.gemfile

@@ -0,0 +1,8 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "kgio", platform: :mri
+gem "rails", "~> 5.0.0"
+
+gemspec path: "../"

gemfiles/rails5.1.gemfile

@@ -0,0 +1,8 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "kgio", platform: :mri
+gem "rails", "~> 5.1.0"
+
+gemspec path: "../"

gemfiles/rails5.2.gemfile

@@ -0,0 +1,8 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "kgio", platform: :mri
+gem "rails", "~> 5.2.0"
+
+gemspec path: "../"

gemfiles/rails6.0.gemfile

@@ -0,0 +1,8 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "kgio", platform: :mri
+gem "rails", "~> 6.0.0"
+
+gemspec path: "../"