Start running Rails from the main branch (#16)

Reviewed-on: #16

config/application.rb

@@ -9,7 +9,7 @@ Bundler.require(*Rails.groups)
 module FamilyBudget
   class Application < Rails::Application
     # Initialize configuration defaults for originally generated Rails version.
-    config.load_defaults 7.1
+    config.load_defaults 8.0
 
     # Please, add to the `ignore` list any other `lib` subdirectories that do
     # not contain `.rb` files, or that should not be reloaded or eager loaded.