Is codespaces-rails going to be upgraded to Rails 8 and Ruby 3.4?

Current codespaces-rails is for Rails 7.1.3~ and Ruby 3.3.0~ so I suppose the repository should be upgraded to [Rails 8.0.x](https://rubyonrails.org/2024/12/13/Rails-Version-8-0-1-has-been-released) and [Ruby 3.4.x](https://www.ruby-lang.org/en/news/2024/12/25/ruby-3-4-1-released/).

In addition, we can now use the `--devcontainer` option to generate the official devcontainer setup that is available for codespaces as well.

Do you have any plans to upgrade the repository to Rails 8?

The issue names no files or tests, so first locate where the repository declares its Rails and Ruby versions and how its Codespaces setup is generated. Compare the current setup with Rails 8.0.x, Ruby 3.4.x, and the --devcontainer option; done means the repository is upgraded to those versions with the intended devcontainer setup.

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