Drop support for older versions of Rails (#58)

.github/workflows/ci.yml

@@ -8,17 +8,23 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        gemfile: [rails_4.0.0.gemfile, rails_5.0.0.gemfile, rails_5.2.3.gemfile, rails_6.0.0.gemfile, rails_6.1.0.gemfile, rails_main.gemfile]
-        ruby_version: [2.4, 2.5, 2.6, 2.7]
+        gemfile: [rails_5.2.0.gemfile, rails_6.0.0.gemfile, rails_6.1.0.gemfile, rails_main.gemfile]
+        ruby_version: [2.3, 2.4, 2.5, 2.6, 2.7]
         exclude:
+          - gemfile: rails_main.gemfile
+            ruby_version: 2.3
           - gemfile: rails_main.gemfile
             ruby_version: 2.4
           - gemfile: rails_main.gemfile
             ruby_version: 2.5
           - gemfile: rails_main.gemfile
             ruby_version: 2.6
+          - gemfile: rails_6.0.0.gemfile
+            ruby_version: 2.3
           - gemfile: rails_6.0.0.gemfile
             ruby_version: 2.4
+          - gemfile: rails_6.1.0.gemfile
+            ruby_version: 2.3
           - gemfile: rails_6.1.0.gemfile
             ruby_version: 2.4
     env:

spec/gemfiles/rails_5.0.0.gemfile → spec/gemfiles/rails_5.2.0.gemfile

@@ -2,4 +2,4 @@ source 'https://rubygems.org'
 
 gemspec path: '../..'
 
-gem 'rails', '~> 5.0.0'
+gem 'rails', '~> 5.2.0'

yaaf.gemspec

@@ -19,8 +19,8 @@ Gem::Specification.new do |spec|
   spec.files = Dir['LICENSE.txt', 'README.md', 'lib/**/*']
   spec.require_paths = ['lib']
 
-  spec.add_dependency 'activemodel', ['>= 4', '< 7']
-  spec.add_dependency 'activerecord', ['>= 4', '< 7']
+  spec.add_dependency 'activemodel', ['>= 5.2', '< 7']
+  spec.add_dependency 'activerecord', ['>= 5.2', '< 7']
 
   spec.add_development_dependency 'database_cleaner-active_record', '~> 1.8.0'
   spec.add_development_dependency 'rake', '~> 13.0.1'