Bootstrap5 migration and minor UI redesign.
Depends on django-mailman3!188 (merged)
See also hyperkitty!498 (merged)
There isn't really any major UI level change (unlike Hyperkitty) and the only major visible changes are in colors and navigation bar on top. Most changes are meant to update the classes to bootstrap5 equivalent and in some cases minor UI fixes.
Edited by Abhilash Raj