Fix 'Kernel.require': cannot load such file -- csv (LoadError)

[1s22s1]

Steps to reproduce

Run bundle exec rake server.

Expected behavior

There is no error.

Actual behavior

There is a error. The log is below.

azarashi@saito:~/src/sinatra.github.com$ bundle exec rake server
rm -rf _site
jekyll serve --watch
/home/azarashi/.rbenv/versions/3.4.3/lib/ruby/gems/3.4.0/gems/jekyll-4.2.2/lib/jekyll.rb:26: warning: logger was loaded from the standard library, but will no longer be part of the default gems starting from Ruby 3.5.0.
You can add logger to your Gemfile or gemspec to silence this warning.
/home/azarashi/.rbenv/versions/3.4.3/lib/ruby/gems/3.4.0/gems/jekyll-4.2.2/lib/jekyll.rb:28: warning: csv was loaded from the standard library, but is not part of the default gems starting from Ruby 3.4.0.
You can add csv to your Gemfile or gemspec to silence this warning.
/home/azarashi/.rbenv/versions/3.4.3/lib/ruby/3.4.0/bundled_gems.rb:82:in 'Kernel.require': cannot load such file -- csv (LoadError)
        from /home/azarashi/.rbenv/versions/3.4.3/lib/ruby/3.4.0/bundled_gems.rb:82:in 'block (2 levels) in Kernel#replace_require'
        from /home/azarashi/.rbenv/versions/3.4.3/lib/ruby/gems/3.4.0/gems/jekyll-4.2.2/lib/jekyll.rb:28:in '<top (required)>'
        from /home/azarashi/.rbenv/versions/3.4.3/lib/ruby/3.4.0/bundled_gems.rb:82:in 'Kernel.require'
        from /home/azarashi/.rbenv/versions/3.4.3/lib/ruby/3.4.0/bundled_gems.rb:82:in 'block (2 levels) in Kernel#replace_require'
        from /home/azarashi/.rbenv/versions/3.4.3/lib/ruby/gems/3.4.0/gems/jekyll-4.2.2/exe/jekyll:8:in '<top (required)>'
        from /home/azarashi/.rbenv/versions/3.4.3/bin/jekyll:25:in 'Kernel#load'
        from /home/azarashi/.rbenv/versions/3.4.3/bin/jekyll:25:in '<main>'

System configuration

Ruby version: ruby 3.4.3 (2025-04-14 revision d0b7e5b6a0) +PRISM [x86_64-linux]