Require Ruby >= 3.3 and update CI Ruby versions

[dduugg]

Summary

Ruby 3.2 is now EOL. This PR raises the minimum supported Ruby to 3.3 (the lowest supported version). The supported set is 3.3 and 3.4 (latest stable 3.4.9; 3.5 is preview-only and not included).

Motivation: resolve Ruby version restrictions from rubyatscale/pack_stats#56, where supporting EOL Ruby forced older/vulnerable transitive dependencies.

Changes

• code_teams.gemspec: required_ruby_version raised from >= 3.2 to >= 3.3.
• .rubocop.yml: TargetRubyVersion raised from 3.2 to 3.3.

Notes

• CI workflows (.github/workflows/*.yml) delegate to rubyatscale/shared-config reusable workflows and contain no inline Ruby version matrices, so no workflow edits were needed.
• No .ruby-version / .tool-versions files exist in this repo.
• No bundle install was run and Gemfile.lock is unchanged.

Bundler

Also bumps BUNDLED WITH in Gemfile.lock to bundler 4.0.15 (latest). The previously pinned bundler version crashes on Ruby head (NameError: uninitialized constant Pathname::SEPARATOR_PAT) — see this failing run. Pinning the current bundler resolves it.