Include value from Exception.stacktrace if available

[mpkorstanje]

🤔 What's changed?

Include value from Exception.stacktrace if available. Fall back to the message otherwise.

This does require v24 of the messages in which the stacktrace was added.

⚡️ What's your motivation?

Closes: #26

🏷️ What kind of change is this?

• ⚡ New feature (non-breaking change which adds new behaviour)

♻️ Anything particular you want feedback on?

📋 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.