Only require necessary railties

With the upgrade from Rails 6.0 to 6.1 active storage
complains about the missing configuration file. Since
we are not using active storage anywhere in the project
the easiest way is to disable it.

See rails/rails#41106

src/api/config/application.rb

@@ -1,6 +1,14 @@
 require_relative 'boot'
 
-require 'rails/all'
+require 'rails'
+require 'active_model/railtie'
+require 'active_job/railtie'
+require 'active_record/railtie'
+require 'action_mailer/railtie'
+require 'action_controller/railtie'
+require 'action_view/railtie'
+require 'sprockets/railtie'
+require 'rails/test_unit/railtie'
 
 # Assets should be precompiled for production (so we don't need the gems loaded then)
 Bundler.require(*Rails.groups(assets: ['development', 'test']))