Use rails 5.2 config

Author: jdleesmiller

config/application.rb

@@ -22,7 +22,7 @@
 module Wedding
   class Application < Rails::Application
     # Initialize configuration defaults for originally generated Rails version.
-    config.load_defaults 5.1
+    config.load_defaults 5.2
 
     # Settings in config/environments/* take precedence over those specified here.
     # Application configuration can go into files in config/initializers