Fix sass deprecation in Bootstrap

[camd]

Relies on #9112 which must be merged first.

This was minor, but still showed up as a deprecation.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 44.44444% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.95%. Comparing base (5d64caf) to head (4daf59e).

Files with missing lines	Patch %	Lines
ui/App.jsx	44.44%	5 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #9113   +/-   ##
=======================================
  Coverage   79.95%   79.95%           
=======================================
  Files         600      600           
  Lines       32560    32560           
  Branches     3310     3310           
=======================================
  Hits        26032    26032           
  Misses       6362     6362           
  Partials      166      166           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[camd]

Abandoning in favor or RSPack approach.