[rubygems/rubygems] Autoload `pathname` at the top level

Otherwise Ruby >= 3.2 gives a warning which makes several specs fail,
and truffleruby rejects it at all.

https://github.com/rubygems/rubygems/commit/ae2878484f

lib/bundler/shared_helpers.rb

@@ -4,14 +4,14 @@ require_relative "version"
 require_relative "rubygems_integration"
 require_relative "current_ruby"
 
+autoload :Pathname, "pathname"
+
 module Bundler
   autoload :WINDOWS, File.expand_path("constants", __dir__)
   autoload :FREEBSD, File.expand_path("constants", __dir__)
   autoload :NULL, File.expand_path("constants", __dir__)
 
   module SharedHelpers
-    autoload :Pathname, "pathname"
-
     def root
       gemfile = find_gemfile
       raise GemfileNotFound, "Could not locate Gemfile" unless gemfile