Spec: Attempt to skip test for Async::Container::Threaded in JRuby.

Author: olleolleolle

spec/async/io/shared_endpoint/server_spec.rb

@@ -67,6 +67,6 @@
 	it_behaves_like Async::IO::SharedEndpoint, described_class
 end
 
-RSpec.describe Async::Container::Threaded, if: RUBY_PLATFORM !~ /darwin/ do
+RSpec.describe Async::Container::Threaded, if: (RUBY_PLATFORM !~ /darwin/ && RUBY_ENGINE != "jruby") do
 	it_behaves_like Async::IO::SharedEndpoint, described_class
 end