Import from https://github.com/ruby/strscan/pull/19

* Use Gemfile instead of Gem::Specification#add_development_dependency.

* Use pend instead of skip for test-unit.

ext/strscan/strscan.gemspec

@@ -25,8 +25,4 @@ Gem::Specification.new do |s|
   s.email = [nil, "kou@cozmixng.org"]
   s.homepage = "https://github.com/ruby/strscan"
   s.licenses = ["Ruby", "BSD-2-Clause"]
-
-  s.add_development_dependency "rake-compiler"
-  s.add_development_dependency "benchmark-driver"
-  s.add_development_dependency "test-unit"
 end

test/strscan/test_ractor.rb

@@ -3,7 +3,7 @@ require 'test/unit'
 
 class TestStringScannerRactor < Test::Unit::TestCase
   def setup
-    skip unless defined? Ractor
+    pend unless defined? Ractor
   end
 
   def test_ractor