Drop support for Rails < 5.2

Author: cjlarose

Appraisals

@@ -1,33 +1,3 @@
-# Bundler >= 2.x do not work with Rails 4.2
-puts `bundle -v`
-
-if (`bundle -v`[/\d+\.\d+\.\d+/]).start_with?('1.17')
-  appraise 'rails-4.2' do
-    gem 'activerecord-jdbcsqlite3-adapter', '~> 1.3.25', platform: :jruby
-    gem 'rails', '4.2.11.3'
-    gem 'rspec-rails', '~> 3.7'
-    gem 'sprockets', '~> 3.7'
-    gem 'sqlite3', '< 1.4.0', platform: :ruby
-    gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw]
-  end
-else
-  puts 'Skipping rails-4.2 for Bundler >= 2.x'
-end
-
-appraise 'rails-5.0' do
-  gem 'activerecord-jdbcsqlite3-adapter', '~> 50.6', platform: :jruby
-  gem 'rails', '5.0.7.2'
-  gem 'rspec-rails', '~> 3.7'
-  gem 'sqlite3', '< 1.4.0', platform: :ruby
-end
-
-appraise 'rails-5.1' do
-  gem 'activerecord-jdbcsqlite3-adapter', '~> 51.6', platform: :jruby
-  gem 'rails', '5.1.7'
-  gem 'rspec-rails', '~> 3.7'
-  gem 'sqlite3', '< 1.4.0', platform: :ruby
-end
-
 appraise 'rails-5.2' do
   gem 'activerecord-jdbcsqlite3-adapter', '~> 52.5', platform: :jruby
   gem 'bootsnap', '~> 1.4'

README.md

@@ -28,13 +28,13 @@ Current version supports and is [tested](.github/workflows/tests.yml#L19) for th
   * [JRuby](https://www.jruby.org) `>= 9.2`
   * [TruffleRuby](https://github.com/oracle/truffleruby) `>= 19.3`
 * Application frameworks
-  * Rails `>= 4.2`, `5` and `6`
+  * Rails `>= 5.2`
   * Padrino
   * Sinatra
 
 For Ruby `2.0` to `2.3` or Rails `3` to `4.1` use version `1.x` of this gem. For older versions of Rails or Ruby use [AppConfig](http://github.com/fredwu/app_config).
 
-For Ruby `2.4` or `2.5`, use version `3.x` of this gem.
+For Ruby `2.4` or `2.5` or Rails `4.2`, `5.0`, or `5.1` use version `3.x` of this gem.
 
 ## Installing