test_cgi_cookie_new_with_domain does not run in 2.6 or earlier

The test added in 107a0c67f922044dc78e2fde94f991206267a6a0 contains a test that uses `*h to merge two string hashes. This does not work under Ruby 2.6 and earlier, making it impossible to test v0.1.0.2 on any Ruby 2.6-compatible implementation.

Error: test_cgi_cookie_new_with_domain(CGICookieTest): TypeError: hash key "name" is not a Symbol
/home/enebo/work/gems/cgi/test/cgi/test_cgi_cookie.rb:65:in `test_cgi_cookie_new_with_domain'
     62: 
     63:   def test_cgi_cookie_new_with_domain
     64:     h = {'name'=>'name1', 'value'=>'value1'}
  => 65:     cookie = CGI::Cookie.new('domain'=>'a.example.com', **h)
     66:     assert_equal('a.example.com', cookie.domain)
     67: 
     68:     cookie = CGI::Cookie.new('domain'=>'1.example.com', **h)

从 test/cgi/test_cgi_cookie.rb 中的 test_cgi_cookie_new_with_domain 开始，检查在 Ruby 2.6 及更早版本下失败信息中显示的调用。使用与 Ruby 2.6 兼容的实现运行此测试，并验证它在两个示例域上都能执行并通过。