fix: Handle resize event in crossterm demo

[heyrict]

This PR pipes crossterm::Event::Resize to the ui, forcing the ui to re-render after resize.

Fixes #250.

[extrawurst]

Hi @heyrict thanks for following up on #250 but I checked this out on my machine and it does not fix the issue. it turns out that when I checkout your fork it works because for some reason it compiles against Crossterm 0.10 while my local repo uses 0.16 - please try your change against recent Crossterm and I think u will see the issue aswell.

The main issue that this shows is: the Cargo.lock file is on .gitignore which allows everyone to build against different sets of versions. Is there any reason for this @fdehau ?

[fdehau]

@extrawurst The reason for the missing Cargo.lock: https://doc.rust-lang.org/cargo/faq.html#why-do-binaries-have-cargolock-in-version-control-but-not-libraries