Merge pull request #1216 from ruby/backports

Backport #1214 to 2.8

rbs.gemspec

@@ -28,7 +28,7 @@ Gem::Specification.new do |spec|
   # Specify which files should be added to the gem when it is released.
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
   spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
-    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features|bin)/}) }
+    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features|bin|steep)/}) }
   end
   spec.extensions = %w{ext/rbs_extension/extconf.rb}