Spec setup: Set user class to Spree::User

With the generated dummy `spree.rb` now running after the default in the
solidus_auth_devise `engine.rb`, we need to make sure that
`config/initializers/spree.rb` contains the correct user class. Before
this commit, it would generate one with the `Spree::LegacyUser`.

Author: mamhoff

Rakefile

@@ -6,6 +6,6 @@ ENV['SKIP_SOLIDUS_BOLT'] = 'true'
 require 'bundler/gem_tasks'
 
 require 'solidus_dev_support/rake_tasks'
-SolidusDevSupport::RakeTasks.install
+SolidusDevSupport::RakeTasks.install(user_class: "Spree::User")
 
 task default: 'extension:specs'

solidus_auth_devise.gemspec

@@ -36,6 +36,6 @@ Gem::Specification.new do |spec|
 
   spec.add_development_dependency 'solidus_backend'
   spec.add_development_dependency 'solidus_frontend'
-  spec.add_development_dependency 'solidus_dev_support', '~> 2.5'
+  spec.add_development_dependency 'solidus_dev_support', '~> 2.10'
   spec.add_development_dependency 'rails-controller-testing'
 end