replace duration with luxon for formatting

[davidjgoss]

🤔 What's changed?

Removes duration as a library for formatting a duration, and replace with luxon.

Also looked at date-fns, being the other of the big two date handling libraries these days, but its functionality for formatting durations didn't match what we need here.

⚡️ What's your motivation?

Fixes #2160. The old library was unmaintained and had a transitive dependency vulnerability.

🏷️ What kind of change is this?

• 🏦 Refactoring/debt/DX (improvement to code design, tooling, documentation etc. without changing behaviour)
• 🐛 Bug fix (non-breaking change which fixes a defect)

📋 Checklist:

• I agree to respect and uphold the Cucumber Community Code of Conduct
• I've changed the behaviour of the code
  • I have added/updated tests to cover my changes.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• Users should know about my change
  • I have added an entry to the "Unreleased" section of the CHANGELOG, linking to this pull request.

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[coveralls]

Coverage: 98.335%. Remained the same when pulling ec10bc1 on feat/durations-rework into 01a929c on main.