rspec-rails 4.0.0 claims to be compatible with ruby < 2.3

[betesh]

What Ruby, Rails and RSpec versions are you using?

Ruby version: 2.2.2 (I know you don't support it anymore. That's the whole point of this bug!)
Rails version: Any
RSpec version: 4.0.0

Observed behaviour

When running ruby 2.2.2, rspec-rails 4.0.0 gets installed with even though it uses the safe navigation operator, which was not introduced until ruby 2.3.0

Expected behaviour

When installing the bundle, bundler should raise a Bundler::VersionConflict because rspec-rails 4.0.0 depends on ruby >= 2.3.0.

Can you provide an example app?

~/rspec-rails-ruby-2.2.2 $ cat test.rb 
#! /usr/bin/env ruby

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'

  gem 'rails'
  gem 'rspec-rails', '= 4.0.0'
end

require 'action_controller'
require 'action_view'
require 'rspec/rails'
~/rspec-rails-ruby-2.2.2 $ rvm 2.3.0 do ./test.rb   # This completes without errors
~/rspec-rails-ruby-2.2.2 $ rvm 2.2.2 do ./test.rb 
~/.rvm/gems/ruby-2.2.2/gems/activesupport-5.2.4.2/lib/active_support/dependencies.rb:291:in `require': ~/.rvm/gems/ruby-2.2.2/gems/rspec-rails-4.0.0/lib/rspec/rails/example/mailer_example_group.rb:25: syntax error, unexpected '.' (SyntaxError)
          options&.each { |key, value| default_u...
                   ^
	from ~/.rvm/gems/ruby-2.2.2/gems/activesupport-5.2.4.2/lib/active_support/dependencies.rb:291:in `block in require'
	from ~/.rvm/gems/ruby-2.2.2/gems/activesupport-5.2.4.2/lib/active_support/dependencies.rb:257:in `load_dependency'
	from ~/.rvm/gems/ruby-2.2.2/gems/activesupport-5.2.4.2/lib/active_support/dependencies.rb:291:in `require'
	from ~/.rvm/gems/ruby-2.2.2/gems/rspec-rails-4.0.0/lib/rspec/rails/example.rb:6:in `<top (required)>'
	from ~/.rvm/gems/ruby-2.2.2/gems/rspec-rails-4.0.0/lib/rspec/rails.rb:14:in `require'
	from ~/.rvm/gems/ruby-2.2.2/gems/rspec-rails-4.0.0/lib/rspec/rails.rb:14:in `<top (required)>'
	from ~/rspec-rails-ruby-2.2.2/test.rb:14:in `require'
	from ~/rspec-rails-ruby-2.2.2/test.rb:14:in `<main>'

[JonRowe]

Yes we're aware, this is a duplicate of #2319 the issue is that we hard support Rails 5 and 6, with all there requisite Ruby versions, but didn't update the version constraint with an effort to soft support Rails 4.2 for this transitionary version, but overlooked a hard minimum ruby version, its hard to fix due to ruybgems rules unforuntately.