[flori/json] skip TruffleRuby

https://github.com/flori/json/commit/bab704eb49

test/json/json_parser_test.rb

@@ -24,6 +24,9 @@ class JSONParserTest < Test::Unit::TestCase
   end if defined?(Encoding::UTF_16)
 
   def test_error_message_encoding
+    # https://github.com/flori/json/actions/runs/6478148162/job/17589572890
+    pend if RUBY_ENGINE == 'truffleruby'
+
     bug10705 = '[ruby-core:67386] [Bug #10705]'
     json = ".\"\xE2\x88\x9A\"".force_encoding(Encoding::UTF_8)
     e = assert_raise(JSON::ParserError) {