Fix Helix integration

I recently solved the same issue [here](https://github.com/thomasschafer/scooter/pull/130) so thought I'd make a PR with the same fix for Serpl! I also added an example keybinding to the readme but happy to remove this if you'd prefer. Note that I had to bump the versions of Crossterm and Ratatui to enable the fix, meaning I had to make some small updates due to breaking changes and deprecation warnings. Resolves https://github.com/yassinebridi/serpl/issues/30