Fix entity_spec.rb

Author: ericproulx

spec/integration/grape_entity/entity_spec.rb

@@ -348,7 +348,7 @@ def call(_env)
       opts = options
       Rack::Builder.app do
         use Spec::Support::EndpointFaker
-        use Grape::Middleware::Error, opts
+        use Grape::Middleware::Error, **opts
         run ErrApp
       end
     end