add test for timeout while getting from stdin

[emiltin]

Added a test to shows that with_timeout() does not return Async::Timeout() if timing out while getting from stdin.

The test can be run with:

% bundle exec sus test/async/task.rb:599
🏁 Finished in 103.3ms; 9.682 assertions per second.
🐇 No slow tests found! Well done!

🤔 Failed assertions:
describe Async::Task with #with_timeout it will timeout while getting from stdin test/async/task.rb:599
	expect #<Errno::ENOENT: No such file or directory @ io_fillbuf - fd:0 <STDIN>> to
		be is_a? Async::TimeoutError
			✗ assertion failed test/async/task.rb:612

Types of Changes

• Added a test

Contribution

• I added tests for my changes.
• I tested my changes locally.
• I agree to the Developer's Certificate of Origin 1.1.

[ioquatix]

This test passes with Select, URing and fails on EPoll. Not sure why, investigating.