Update Ruby dependencies for Cucumber suite

[lochnesh]

Summary

• update the Gemfile to target modern releases of aruba, cucumber, json, and add the standalone logger gem
• regenerate the lockfile with Ruby 3.4.4 and Bundler 2.6.7 metadata so the Cucumber suite can install on current Ruby versions
• build Ruby 3.3.9 and Bundler 2.6.7 in the Dockerfile so CI runs against the refreshed toolchain

Testing

• bundle exec cucumber (fails: exercise executables are not present in PATH in this environment)
• ./verify.sh (fails: mix local.hex cannot download metadata from https://builds.hex.pm because it returns HTTP 503)

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https://chatgpt.com/codex/tasks/task_b_68d5afdbcd348321ade487ed88e84444