Merge branch '47959-rails5-redis-timewithzone' into 'master'

Resolve "[Rails5] expected "2018-05-07 13:53:08 UTC" to be an instance of ActiveSupport::TimeWithZone"

Closes #47959

See merge request gitlab-org/gitlab-ce!20000

app/models/concerns/redis_cacheable.rb

@@ -48,7 +48,7 @@ module RedisCacheable
 
   def cast_value_from_cache(attribute, value)
     if Gitlab.rails5?
-      self.class.type_for_attribute(attribute).cast(value)
+      self.class.type_for_attribute(attribute.to_s).cast(value)
     else
       self.class.column_for_attribute(attribute).type_cast_from_database(value)
     end