Bootstrap5 upgrade fixes (#69)

* replace all camelCased scss variables to kebab-case

* fix bootstrap 5 variable naming

* upgrade all view files to bootstrap 5

app/views/people/_show_left_jubla.html.haml

@@ -1,3 +1,3 @@
 - if entry.alumnus_only?
-  %h2= t('.contactable_by')
+  %h2.mt-3= t('.contactable_by')
   = render_attrs(entry, :contactable_by_federation, :contactable_by_state, :contactable_by_region, :contactable_by_flock)