Downgrade notify from v5 to v4

[dnaka91]

This downgrades the notify crate back from v5 to v4 as the latest version is still missing some important features. Especially event debouncing is missing, which causes multiple compiles on file save in VSCode and Emacs. Sticking with v4 seems to be the recommended way from the maintainers as well.

This might eventually help fixing the issues with Vim too.

Also, see #232, #331.

Fixes #238

Checklist

• Updated CHANGELOG.md describing pertinent changes.
• Updated README.md with pertinent info (may not always apply).
• Updated site content with pertinent info (may not always apply).
• Squash down commits to one or two logical commits which clearly describe the work you've done. If you don't, then Dodd will 🤓.

[thedodd]

+1 seems reasonable. I think I've historically already flopped between v4 & v5 once before haha. Oh well. IIRC, the only reason I tried to move away from v4 was due to the sync interface ... but it is not a big deal.

[dnaka91]

Thanks, @thedodd. I wasn't a big fan of pulling the std::sync::mpsc channel back in, neither. Even have to start up an extra thread just to forward messages to the async channel.

But it helps with the linked issues.

Seeing some activity on the notify crate's repo as well, so hopes are we maybe can get a full v5 release this year. Might open an issue on their site, asking for a new v4 release that just updates the dependencies. As it stands, this introduces quite a bit of dependency duplicates (luckily no public API facing ones).