Update to EGUI 0.31

[rnd-ash]

No description provided.

[RegenJacob]

warning: use of deprecated field egui::PlatformOutput::copied_text: Use Context::copy_text or PlatformOutput::commands instead
   --> src/ui.rs:317:25
    |
317 |                         o.copied_text = out_string;
    |                         ^^^^^^^^^^^^^
    |
    = note: #[warn(deprecated)] on by default
    

It seems like they changed how text copying works in the latest release.
Could you update the approach?

[RegenJacob]

I'll merge it for now.

Because of your inactivity I'll fix the deprecation warnings myself.