build(deps): update itertools requirement from 0.11 to 0.12 in /demo

Updates the requirements on [itertools](https://github.com/rust-itertools/itertools) to permit the latest version.
- [Changelog](https://github.com/rust-itertools/itertools/blob/master/CHANGELOG.md)
- [Commits](rust-itertools/itertools@v0.11.0...v0.12.1)

---
updated-dependencies:
- dependency-name: itertools
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

demo/Cargo.toml

@@ -25,7 +25,7 @@ iced = { version = "0.12", features = [
   "tokio",
   "lazy",
 ], optional = true }
-itertools = "0.11"
+itertools = "0.12"
 crossbeam-channel = "0.5"
 image_rs = { package = "image", version = "0.24", optional = true }
 anyhow = "1.0"