Pass trusted_proxies to action_dispatch as IPAddrs instead of strings

Without this setting your own trusted_proxies does not work.

config/initializers/trusted_proxies.rb

-Rails.application.config.action_dispatch.trusted_proxies =
+Rails.application.config.action_dispatch.trusted_proxies = (
   [ '127.0.0.1', '::1' ] + Array(Gitlab.config.gitlab.trusted_proxies)
+).map { |proxy| IPAddr.new(proxy) }