[FIX] Sponsor logos overlapping on Contacts page

[marcellintacite]

Here's the issue : #3800

The original layout used Bootstrap's grid system (row, row-cols-*, and col), which was causing the logos to shrink and overlap before they wrapped. This was due to the default flex-shrink behavior of the col class.

This PR replaces the grid classes with a simpler, more flexible flexbox approach. The parent ul element now uses d-flex and flex-wrap, allowing the list items to wrap to a new line naturally when the container shrinks.
By also adding a gap-4 class to the container, we ensure there is consistent space between the logos, preventing them from touching or overlapping.

Before submitting your request, please make sure the following conditions are met:

• Add a changelog entry for your change in CHANGES.md
• When adding a configuration variable, please make sure to
  document it in docs/source/configuration.rst
• Please add a test for your change. Tests can be run in the commandline
  with make check or you can run them in the browser by running make serve
  and then opening http://localhost:8000/tests.html.

[jcbrand]

Hi @marcellintacite, could you please fix the merge conflict in this branch?

[marcellintacite]

Hi @marcellintacite, could you please fix the merge conflict in this branch?

I am working on it and also i have issue with test. I am trying to figure it out

[marclaporte]

There is only a change in CHANGES.md now