Add comment to clarify usage of Oj.strict_load

Author: bangseongbeom

test/test_urlpattern.rb

@@ -18,6 +18,7 @@ def test_that_it_has_a_version_number
   URLPATTERNTESTDATA = begin
     UNDERSCORE = { baseURL: :base_url, ignoreCase: :ignore_case }.freeze
 
+    # Use `Oj.strict_load` with `allow_invalid_unicode` to work around `JSON::ParserError` (incomplete surrogate pair).
     Oj.strict_load(File.read(
                      File.join(__dir__, "fixtures", "urlpatterntestdata.json"), encoding: Encoding::UTF_8
                    ), { allow_invalid_unicode: true, symbol_keys: true }).map do |entry|