Add application implementation of Rails secrets because of deprecation (

#317)

config/application.rb

@@ -9,10 +9,16 @@
 module Open311status
   class Application < Rails::Application
     # Initialize configuration defaults for originally generated Rails version.
-    config.load_defaults 6.1
+    config.load_defaults 7.1
 
     config.active_job.queue_adapter = :good_job
 
+    config.secrets = config_for(:secrets)
+    config.secret_key_base = config.secrets[:secret_key_base]
+    def secrets
+      config.secrets
+    end
+
     # 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