Fix slugify test

test/test_utils.rb

@@ -183,7 +183,7 @@ class TestUtils < JekyllUnitTest
     end
 
     should "replace everything else but ASCII characters" do
-      assert_equal "the-config.yml-file", Utils.slugify("The _config.yml file?", mode: "ascii")
+      assert_equal "the-config-yml-file", Utils.slugify("The _config.yml file?", mode: "ascii")
     end
 
     should "only replace whitespace if mode is raw" do