Remove unused keen-ui dependency

[MisRob]

Description

• Removes unused keen-ui dependency
• I also added a small fix to changelog item link format

Changelog

• #531
  • Description: Remove unused keen-ui dependency
  • Products impact: none
  • Addresses: -
  • Components: -
  • Breaking: -
  • Impacts a11y: -
  • Guidance: -

Steps to test

You could confirm that the dependency is indeed not used from anywhere.

Testing checklist

• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
• Critical and brittle code paths are covered by unit tests
• The change is described in the changelog section above

Reviewer guidance

• Is the code clean and well-commented?
• Are there tests for this change?
• Are all UI components LTR and RTL compliant (if applicable)?
• Add other things to check for here

After review

• The changelog item has been pasted to the CHANGELOG.md

[MisRob]

Relatedly I closed #495

[nucleogenesis]

I gave it a smoke test by running the local dev server and all seemed to go alright then I smoke tested it against Kolibri release-v0.16.x branch using devserver-with-kds pointing to this local branch. No issues there.

[MisRob]

Alright, thank you @nucleogenesis