rtcompat scheduler::test::suspend_and_resume_with_sleep is flaky

Pipeline failure here: https://gitlab.torproject.org/tpo/core/arti/-/pipelines/43712 https://gitlab.torproject.org/tpo/core/arti/-/jobs/151912

---- scheduler::test::suspend_and_resume_with_sleep stdout ----
thread 'scheduler::test::suspend_and_resume_with_sleep' panicked at 'assertion failed: sch.next().now_or_never().is_none()', crates/tor-rtcompat/src/scheduler.rs:386:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
failures:
    scheduler::test::suspend_and_resume_with_sleep
test result: FAILED. 44 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.89s