RSPEC 6.1.2 and Rails 7.1.3: Could not find a JavaScript runtime

Question

My project is to refactor an old application running on Rails 5.1 to set it up on Rails 7. I will use TDD (with RSPEC) to re-implement feature after feature, and add improvements. My first step is to setup the Rails 7 environment including RSPEC, and some base gems such as Devise, Cancancan...

Gemfile

    source "https://rubygems.org"
    git_source(:github) { |repo| "https://github.com/#{repo}.git" }
    
    ruby "3.3.0"
    
    gem "rails", "~> 7.1"
    gem "sprockets-rails"
    gem "pg", "~> 1.5.6"
    gem "puma", "~> 5.0"
    gem "importmap-rails"
    gem "turbo-rails"
    gem "stimulus-rails"
    gem "jbuilder"
    # Domain specific logging
    gem 'multi_logger'
    
    gem "tzinfo-data", platforms: %i[ mingw mswin x64_mingw jruby ]
    gem "bootsnap", require: false
    
    ### Features
    # Authentication and Authorisations
    gem 'devise'
    gem 'devise-jwt'
    gem 'devise-security'
    gem 'cancancan', '~> 3.0'
    gem "bcrypt", "~> 3.1.7"
    
    ### Frontend publication
    gem 'bootstrap', '~> 5.2'
    gem "sassc-rails"
    gem 'pagy'
    
    group :development, :test do
      gem "debug", platforms: %i[ mri mingw x64_mingw ]
      gem 'annotate'
      gem 'rspec-rails', '~> 6.1'
    end

    group :development do
      # Use console on exceptions pages [https://github.com/rails/web-console]
      gem "web-console"
    end
    
    group :test do
      # Use system testing [https://guides.rubyonrails.org/testing.html#system-testing]
      gem "capybara"
      gem "selenium-webdriver"
      gem "webdrivers"
      gem 'database_cleaner-active_record'
      gem 'factory_bot_rails'
      gem 'faker'
      gem 'shoulda-matchers'
    end

I did not paste a single line of code yet, I am only configuring the Rails 7 framework. For this project, I use Codesandbox who provides a Docker container, which was upgraded to Ruby 3.3.0.

Dockerfile

# Dockerfile.rails
FROM ruby:3.1.2 AS rails-toolbox
# Install rails
RUN gem install rails bundler

Installing Rails 7.1, I expected not to need an extra JavaScript runtime anymore. But when configuring RSPEC, I get the following error :

   rails generate rspec:install
   /usr/local/rvm/gems/default/gems/execjs-2.9.1/lib/execjs/runtimes.rb:68:in `autodetect': Could not find a JavaScript runtime. See https://github.com/rails/execjs for a list of available runtimes. (ExecJS::RuntimeUnavailable)

Is there a way to workaround this issue?