Update configuration after the Rails upgrade

Ran `bin/rake rails:upgrade` and went through all the changes.

Co-Authored-By: Dan Rice <dnrce@users.noreply.github.com>

config/application.rb

@@ -1,4 +1,4 @@
-require File.expand_path('../boot', __FILE__)
+require_relative 'boot'
 
 require 'rails/all'
 
@@ -33,7 +33,5 @@ module Tracksapp
 
     # configure Tracks to handle deployment in a subdir
     config.relative_url_root = SITE_CONFIG['subdir'] if SITE_CONFIG['subdir']
-
-    config.middleware.insert_after ActionDispatch::ParamsParser, ActionDispatch::XmlParamsParser
   end
 end