[rubygems/rubygems] Skip integration test for rake package task.

https://github.com/rubygems/rubygems/commit/ca8afc01a3

test/rubygems/test_rake_package.rb

@@ -6,6 +6,8 @@ require "open3"
 class TestRakePackage < Minitest::Test
 
   def test_builds_ok
+    skip unless File.exists?(File.expand_path("../../../Rakefile", __FILE__))
+
     output, status = Open3.capture2e("rake package")
 
     assert_equal true, status.success?, <<~MSG.chomp