Revert change to fixtures task

Reverted change to fixtures task since going by
#789
the original task (`db:structure:load`) has been
changed to load fixtures instead.

Author: lenikadali

backend/lib/tasks/app.rake

@@ -44,7 +44,7 @@ namespace :app do
       Rake::Task["db:create"].invoke
       Rake::Task["db:migrate"].invoke
     end
-    # Rake::Task["db:schema:load"].invoke
+    Rake::Task["db:fixtures:load"].invoke
     Rake::Task["db:seed"].invoke
   rescue ::PG::ObjectInUse => e
     puts "\n#{e.message}.".red