upgrade html-formatter for attachment improvements

[davidjgoss]

🤔 What's changed?

Upgrade to the latest html-formatter.

⚡️ What's your motivation?

Brings in ability to download attachments like PDFs that aren't viewable directly in the report - see cucumber/react-components#333

Fixes #2277.

🏷️ What kind of change is this?

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

📋 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: 98.505%. remained the same when pulling 6321443 on html-formatter-20-4-0 into aea9e8b on main.