Allow Solidus 4 on the test extension

Author: waiting-for-dev

lib/solidus_dev_support/templates/extension/extension.gemspec.tt

@@ -29,7 +29,7 @@ Gem::Specification.new do |spec|
   spec.executables = files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_dependency 'solidus_core', ['>= 2.0.0', '< 4']
+  spec.add_dependency 'solidus_core', ['>= 2.0.0', '< 5']
   spec.add_dependency 'solidus_support', '~> 0.5'
 
   spec.add_development_dependency 'solidus_dev_support', '<%= SolidusDevSupport.gem_version.approximate_recommendation %>'