Omit failure on JRuby and truffleruby

Author: nobu

test/pathname/test_pathname.rb

@@ -503,6 +503,8 @@ def test_initialize_nul
   end
 
   def test_initialize_encoding
+    omit "https://github.com/jruby/jruby/issues/9120" if RUBY_ENGINE == "jruby"
+    omit "https://github.com/truffleruby/truffleruby/issues/4047" if RUBY_ENGINE == "truffleruby"
     assert_raise(Encoding::CompatibilityError) { Pathname.new("a".encode(Encoding::UTF_32BE)) }
   end