Use `bg-body` for tab navigation

[stefanw]

In order to support Bootstrap color modes bg-white should be avoided.

[codecov[bot]]

Codecov Report

Merging #138 (4629b25) into master (3f88d49) will not change coverage. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #138   +/-   ##
=======================================
  Coverage   86.81%   86.81%           
=======================================
  Files         119      119           
  Lines        3086     3086           
  Branches      329      329           
=======================================
  Hits         2679     2679           
  Misses        300      300           
  Partials      107      107           

Impacted Files	Coverage Δ
...cms_frontend/contrib/tabs/frameworks/bootstrap5.py	50.00% <100.00%> (ø)

[fsbraun]

@stefanw Thank you very much for the PR. Can you quickly add a note in the changelog?

[fsbraun]

Thank you!