devise 4.9.4 以下由来で未だに発生している deprecation warning:
DEPRECATION WARNING: `Rails.application.secrets` is deprecated in favor of `Rails.application.credentials` and will be removed in Rails 7.2. (called from <main> at /app/config/environment.rb:5)
Related Issues, PRs:
https://github.com/heartcombo/devise/issues/5644
https://github.com/heartcombo/devise/pull/5645
Monkey patch:
https://github.com/JunichiIto/everydayrails-rspec-jp-2024/commit/84401474a705fa3cf9b15df0475e6e00a260f442
自分で先にsecret_keyをsecret_key_baseから用意してあげてしまえば良い.