[rubygems/rubygems] Unify loading Gem::Requirement

It was being explicitly required from `Gem::Specification` but also a
strange autoload was set for it at `Gem::Version`. The autoload was non
standard because it should've been done in the `Gem` module, not in
`Gem::Specification`, since that's where the constant is expected to get
defined. Doing this might get deprecated in the future, and it was not
being effective anyways due to the explicit require.

Unify everything with an `autoload` at the right place.

https://github.com/rubygems/rubygems/commit/174ea3e24c

lib/rubygems.rb

@@ -1303,6 +1303,7 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
   autoload :NameTuple,          File.expand_path('rubygems/name_tuple', __dir__)
   autoload :PathSupport,        File.expand_path('rubygems/path_support', __dir__)
   autoload :RequestSet,         File.expand_path('rubygems/request_set', __dir__)
+  autoload :Requirement,        File.expand_path('rubygems/requirement', __dir__)
   autoload :Resolver,           File.expand_path('rubygems/resolver', __dir__)
   autoload :Source,             File.expand_path('rubygems/source', __dir__)
   autoload :SourceList,         File.expand_path('rubygems/source_list', __dir__)

lib/rubygems/specification.rb

@@ -10,7 +10,6 @@ require_relative 'deprecate'
 require_relative 'basic_specification'
 require_relative 'stub_specification'
 require_relative 'platform'
-require_relative 'requirement'
 require_relative 'util/list'
 
 ##

lib/rubygems/version.rb

@@ -153,8 +153,6 @@ require_relative "deprecate"
 # a zero to give a sensible result.
 
 class Gem::Version
-  autoload :Requirement, File.expand_path('requirement', __dir__)
-
   include Comparable
 
   VERSION_PATTERN = '[0-9]+(?>\.[0-9a-zA-Z]+)*(-[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?'.freeze # :nodoc: