Resolve undefined method `migration_context'

When upgrading our apps to rails version 7.2:

Publish: DFE-Digital/publish-teacher-training#4445

Apply: DFE-Digital/apply-for-teacher-training#9692

Register: DFE-Digital/register-trainee-teachers#4562

We are getting the following error:

NoMethodError: undefined method `migration_context' for #<ActiveRecord::ConnectionAdapters::PostgreSQLAdapter:0x0000000000c620

raise ActiveRecord::PendingMigrationError if ActiveRecord::Base.connection.migration_context.needs_migration?

This is because of breaking changes and deprecation in rails 7.2:

ActiveRecord::Base.connection was changed to with_connection:

- https://blog.saeloun.com/2024/07/01/rails-adds-activerecord-base-with-connection/

This deprecation meant that rspec had to be upgraded:
- rspec/rspec-rails#2661

Set functional versions of the rspec-rails and rails gems depending on what version of rails you are using.

Appraisals

@@ -1,12 +1,20 @@
 appraise "rails-6" do
+  gem "rspec-rails", "5.1.2"
   gem "rails", "6.0.6"
   gem 'psych', '< 4'
 end
 
 appraise "rails-6.1" do
+  gem "rspec-rails", "6.1.3"
   gem "rails", "6.1.7"
 end
 
 appraise "rails-7" do
+  gem "rspec-rails", "6.1.3"
   gem "rails", "7.0.4"
 end
+
+appraise "rails-7.2" do
+  gem "rspec-rails", "6.1.3"
+  gem "rails", "7.2"
+end