Defer loading XmlMini until it's needed

It's used for {Array,Hash}#to_xml, but that doesn't seem worth loading
by default.

Author: matthewd

activesupport/lib/active_support/core_ext/array/conversions.rb

@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require "active_support/xml_mini"
 require "active_support/core_ext/hash/keys"
 require "active_support/core_ext/string/inflections"
 require "active_support/core_ext/object/to_param"

activesupport/lib/active_support/core_ext/hash/conversions.rb

@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require "active_support/xml_mini"
 require "active_support/core_ext/object/blank"
 require "active_support/core_ext/object/to_param"
 require "active_support/core_ext/object/to_query"