pal/hermit: correctly round up microseconds in `Thread::sleep` This fixes the Hermit-related part of https://github.com/rust-lang/rust/issues/129212 and thus the whole issue, since ESP-IDF is already fixed, as far as I understand. Fixes https://github.com/rust-lang/rust/issues/129212 r? `@workingjubilee` CC: `@stlankes`