Enable FactoryBot/AttributeDefinedStatically

See https://robots.thoughtbot.com/deprecating-static-attributes-in-factory_bot-4-11

spec/factories/roles.rb

@@ -2,22 +2,22 @@
 
 FactoryBot.define do
   factory :role do
-    name 'my role'
+    name { 'my role' }
 
     factory :organizer_role do
-      name 'organizer'
+      name { 'organizer' }
     end
 
     factory :cfp_role do
-      name 'cfp'
+      name { 'cfp' }
     end
 
     factory :info_desk_role do
-      name 'info_desk'
+      name { 'info_desk' }
     end
 
     factory :volunteers_coordinator_role do
-      name 'volunteers_coordinator'
+      name { 'volunteers_coordinator' }
     end
   end
 end