Fix full error message test on Rails 6

Before Rails 6, `#human_attribute_name` was called with an symbol as the
first argument (`:name`) which made the switch case execute the `else`
branch (calling `attribute.to_s.humanize`). Ref: https://github.com/rails/rails/blob/5-2-stable/activemodel/lib/active_model/errors.rb#L370

On Rails 6, `#human_attribute_name` is always called with a String
(`"name"`) which made our switch case to execute the first branch.
Since the attribute name was not the most important part of the test -
the full error message is what we care about - I decided to change the
test in order to make it work on both versions.

References:
- https://github.com/rails/rails/blob/6-0-stable/activemodel/lib/active_model/errors.rb#L414
- https://github.com/rails/rails/blob/6-0-stable/activemodel/lib/active_model/errors.rb#L448

test/form_builder/wrapper_test.rb

@@ -161,7 +161,7 @@ class WrapperTest < ActionView::TestCase
   test 'custom wrappers can have full error message on attributes' do
     swap_wrapper :default, custom_wrapper_with_full_error do
       with_form_for @user, :name
-      assert_select 'span.error', "Name cannot be blank"
+      assert_select 'span.error', "Super User Name! cannot be blank"
     end
   end
 

test/support/models.rb

@@ -204,7 +204,7 @@ class User
 
   def self.human_attribute_name(attribute, options = {})
     case attribute
-      when 'name'
+      when 'name', :name
         'Super User Name!'
       when 'description'
         'User Description!'