Update files for Rails 6.1

config/application.rb

@@ -1,6 +1,6 @@
-require_relative 'boot'
+require_relative "boot"
 
-require 'rails/all'
+require "rails/all"
 
 # Require the gems listed in Gemfile, including any gems
 # you've limited to :test, :development, or :production.
@@ -9,12 +9,12 @@ Bundler.require(*Rails.groups)
 module Projekteuler
   class Application < Rails::Application
     # Initialize configuration defaults for originally generated Rails version.
-    config.load_defaults 6.0
+    config.load_defaults 6.1
 
-    # Settings in config/environments/* take precedence over those specified here.
-    # Application configuration can go into files in config/initializers
-    # -- all .rb files in that directory are automatically loaded after loading
-    # the framework and any gems in your application.
+    # Configuration for the application, engines, and railties goes here.
+    #
+    # These settings can be overridden in specific environments using the files
+    # in config/environments, which are processed later.
 
     config.action_dispatch.default_headers = {
         'X-Frame-Options' => 'DENY',