Use the adequate key to read Redis connection URL.

The format of the `config/resque.yml.example` file has changed and we
need to adjust the reading of the connection URL.

lib/gitlab/geo/update_queue.rb

@@ -89,7 +89,7 @@ module Gitlab
         redis_config_file = Rails.root.join('config', 'resque.yml')
 
         redis_url_string = if File.exist?(redis_config_file)
-                             YAML.load_file(redis_config_file)[Rails.env]
+                             YAML.load_file(redis_config_file)[Rails.env][:url]
                            else
                              'redis://localhost:6379'
                            end