Auto merge of #84055 - kornelski:z-edition, r=petrochenkov

Auto merge of #84055 - kornelski:z-edition, r=petrochenkov

Don't tell users to use a nightly flag on the stable channel

When a crate requires a newer edition, currently rustc tells users to use `-Z unstable-options`. This is not ideal, because:

* This flag doesn't work on the stable channel, so solution to one error only causes another error, which is frustrating.

* Directs users towards the nightly channel, which is not necessarily the correct solution. Once the next edition is released, this message will be mostly seen by users of out-of-date stable Rust versions who merely need to update their Rust to the latest stable.