rm::test_rm_deep_1 test fails: too many open files

[jgarzik]

MacOS 14.5 fails thusly:

% GETTEXT_SYSTEM=1 GETTEXT_DIR=/usr/local cargo test -p posixutils-tree --test integration rm::test_rm_deep_1 -- --nocapture
    Finished `test` profile [unoptimized + debuginfo] target(s) in 0.07s
     Running tests/integration.rs (target/debug/deps/integration-1e07fe9a2d399161)

running 1 test
thread 'rm::test_rm_deep_1' panicked at tree/tests/rm/mod.rs:175:34:
called `Result::unwrap()` on an `Err` value: Os { code: 24, kind: Uncategorized, message: "Too many open files" }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
test rm::test_rm_deep_1 ... FAILED

failures:

failures:
    rm::test_rm_deep_1

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 96 filtered out; finished in 0.08s

error: test failed, to rerun pass `-p posixutils-tree --test integration`