Fix parent class name generator for rails 6 (lynndylanhurley#1414)

Author: MaicolBen

lib/generators/devise_token_auth/install_generator.rb

@@ -26,7 +26,7 @@ def create_user_model
         inclusion = 'include DeviseTokenAuth::Concerns::User'
         unless parse_file_for_line(fname, inclusion)
 
-          active_record_needle = (Rails::VERSION::MAJOR == 5) ? 'ApplicationRecord' : 'ActiveRecord::Base'
+          active_record_needle = (Rails::VERSION::MAJOR >= 5) ? 'ApplicationRecord' : 'ActiveRecord::Base'
           inject_into_file fname, after: "class #{user_class} < #{active_record_needle}\n" do <<-'RUBY'
             # Include default devise modules.
             devise :database_authenticatable, :registerable,

test/lib/generators/devise_token_auth/install_generator_test.rb

@@ -70,7 +70,7 @@ class InstallGeneratorTest < Rails::Generators::TestCase
         case DEVISE_TOKEN_AUTH_ORM
         when :active_record
           # account for rails version 5
-          active_record_needle = (Rails::VERSION::MAJOR == 5) ? 'ApplicationRecord' : 'ActiveRecord::Base'
+          active_record_needle = (Rails::VERSION::MAJOR >= 5) ? 'ApplicationRecord' : 'ActiveRecord::Base'
 
           @f = File.open(@fname, 'w') do |f|
             f.write <<-RUBY

test/lib/generators/devise_token_auth/install_generator_with_namespace_test.rb

@@ -75,7 +75,7 @@ class InstallGeneratorTest < Rails::Generators::TestCase
         case DEVISE_TOKEN_AUTH_ORM
         when :active_record
           # account for rails version 5
-          active_record_needle = (Rails::VERSION::MAJOR == 5) ? 'ApplicationRecord' : 'ActiveRecord::Base'
+          active_record_needle = (Rails::VERSION::MAJOR >= 5) ? 'ApplicationRecord' : 'ActiveRecord::Base'
 
           @f = File.open(@fname, 'w') do |f|
             f.write <<-RUBY