Async Rust can be a pleasure to work with (without `Send + Sync + 'static`)

https://emschwartz.me/async-rust-can-be-a-pleasure-to-work-with-without-send-sync-static/ · Async Rust is powerful. And it can be a pain to work with (and learn). Async Rust can be a pleasure to work with, though, if we can do it without `Send + Sync + 'static`.