Use --update=none instead of -n for copy in cache.rb (heroku#1583)

* Use `--update=none` instead of `-n` for `copy` in `cache.rb`

* Changelog

* Fix CI failure

```
  1) LanguagePack::Helpers::OutdatedRubyVersion handles arm 💪 architecture on heroku-24
     Failure/Error: expect(outdated.suggested_ruby_minor_version).to eq("3.3.7")
       expected: "3.3.7"
            got: "3.3.8"
       (compared using ==)
     # ./vendor/bundle/ruby/3.1.0/gems/rspec-support-3.13.1/lib/rspec/support.rb:110:in `block in <module:Support>'
```

3.1 is EOL now and shouldn't change. We should use that.

---------

Co-authored-by: Jan Nash <jnash@jnash.de>

Author: schneems

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## [Unreleased]
 
+- Fix warning message about `cp -n` (https://github.com/heroku/heroku-buildpack-ruby/pull/1583)
 
 ## [v302] - 2025-04-16
 

lib/language_pack/cache.rb

@@ -58,7 +58,7 @@ def load_without_overwrite(path, dest=nil)
     return unless @cache_base
 
     dest ||= path
-    copy (@cache_base + path), dest, '-a -n'
+    copy (@cache_base + path), dest, '-a --update=none'
   end
 
   # copy cache contents

spec/helpers/outdated_ruby_version_spec.rb

@@ -23,7 +23,7 @@
   end
 
   it "handles arm 💪 architecture on heroku-24" do
-    ruby_version = LanguagePack::RubyVersion.new("ruby-3.3.0")
+    ruby_version = LanguagePack::RubyVersion.new("ruby-3.1.0")
     fetcher = LanguagePack::Fetcher.new(
       LanguagePack::Base::VENDOR_URL,
       stack: "heroku-24",
@@ -35,7 +35,7 @@
     )
 
     outdated.call
-    expect(outdated.suggested_ruby_minor_version).to eq("3.3.7")
+    expect(outdated.suggested_ruby_minor_version).to eq("3.1.7")
   end
 
   it "finds the latest version on a stack" do