Behave decorator title variants

[kieran-ryan]

🤔 What's changed?

• Support for title variants of Behave's decorators (Step, Given, When, Then)

⚡️ What's your motivation?

• Support all Behave decorators - ensuring compatibility for users using those variants

🏷️ What kind of change is this?

• :bug: Bug fix (non-breaking change which fixes a defect)

📋 Checklist:

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