Replace SVG asset with Custom mascot (#8766)

spec/views/about/show.html.haml_spec.rb

@@ -18,6 +18,7 @@ describe 'about/show.html.haml', without_verify_partial_doubles: true do
                                 open_registrations: false,
                                 thumbnail: nil,
                                 hero: nil,
+                                mascot: nil,
                                 user_count: 0,
                                 status_count: 0,
                                 contact_account: nil,