Only set property for Rails 7, it has been removed on master

https://github.com/rails/rails/pull/44827

test/rails_app/config/application.rb

@@ -50,7 +50,7 @@ module RailsApp
       Rails.application.config.active_record.sqlite3.represent_boolean_as_integer = true
     end
 
-    if Devise::Test.rails7_and_up?
+    if Devise::Test.rails70?
       config.active_record.legacy_connection_handling = false
     end
   end

test/rails_app/config/boot.rb

@@ -8,8 +8,8 @@ module Devise
   module Test
     # Detection for minor differences between Rails versions in tests.
 
-    def self.rails7_and_up?
-      Rails::VERSION::MAJOR >= 7
+    def self.rails70?
+      Rails.version.start_with? '7.0'
     end
 
     def self.rails6_and_up?