repl::pty_unpaired_braces is flaky

[dsherret]

---- repl::pty_unpaired_braces stdout ----
command /Users/runner/work/deno/deno/target/release/deno repl
command cwd /var/folders/bc/7ycrpl196j7dsckgtn2m6g800000gn/T/deno-cli-testxkvw7c
command /Users/runner/work/deno/deno/target/release/deno repl
command cwd /var/folders/bc/7ycrpl196j7dsckgtn2m6g800000gn/T/deno-cli-testsSOJiM
command /Users/runner/work/deno/deno/target/release/deno repl
command cwd /var/folders/bc/7ycrpl196j7dsckgtn2m6g800000gn/T/deno-cli-testEdcILr
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""
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Next text: ""
thread 'repl::pty_unpaired_braces' panicked at tests/util/server/src/pty.rs:41:11:
Timed out.
stack backtrace:
   0:        0x10b5af8e5 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h46bc8e86d021398c
   1:        0x10b3eee53 - core::fmt::write::h1c24e945c7ef8357
   2:        0x10b5b29ee - std::io::Write::write_fmt::hea454fdd323d68d8
   3:        0x10b5b23b9 - std::sys_common::backtrace::print::hdbfcabb7d363540a
   4:        0x10b5b20c2 - std::panicking::default_hook::***closure***::hecb24382dfeeea98
   5:        0x10b5b1c0e - std::panicking::default_hook::h78dca947ab9e89eb
   6:        0x10b5b2d92 - std::panicking::rust_panic_with_hook::hb83cee65df04957a
   7:        0x10b5b2afc - std::panicking::begin_panic_handler::***closure***::hbe6e44d88f82bc77
   8:        0x10b5b2a89 - std::sys_common::backtrace::__rust_end_short_backtrace::h6560cb9c1f1224c1
   9:        0x10b5b2a76 - _rust_begin_unwind
  10:        0x10c9f8325 - core::panicking::panic_fmt::h2aac8cf45f7ae617
  11:        0x10b6308c3 - test_server::pty::Pty::new::hecd59951dddeeb9c
  12:        0x10b1f207f - core::ops::function::FnOnce::call_once::hf03a90ae6422eb9e
  13:        0x10b5ce782 - test::__rust_begin_short_backtrace::h40ce36891ca37b4e
  14:        0x10b5cb9d1 - test::run_test::***closure***::haa1559c506895862
  15:        0x10b5ceac0 - std::sys_common::backtrace::__rust_begin_short_backtrace::hb20eaca03f887988
  16:        0x10b5ce8f8 - core::ops::function::FnOnce::call_once***vtable.shim***::h1f41e11678d9c890
  17:        0x10b5b4fe9 - std::sys::pal::unix::thread::Thread::new::thread_start::h679ffa03f8a73496
  18:     0x7ff80f9fb1d3 - __pthread_start


failures:
    repl::pty_unpaired_braces

https://github.com/denoland/deno/actions/runs/8904067867/job/24452793475

[dsherret]

I think this would only happen when the CI is very slow.