Ruby index.ruby-china.com/gems 的相关 gem 是不是有问题了，开始报 503 错了。
bundle update 报错了，Gem::RemoteFetcher::FetchError bad response Service Temporarily Unavailable 503
Retrying download gem from https://gems.ruby-china.com/ due to error (2/4): Gem::RemoteFetcher::FetchError bad response Service Temporarily Unavailable 503 (https://index.ruby-china.com/gems/bigdecimal-3.3.0.gem) 一系列的报错。
