Update iced_graphics requirement from 0.9 to 0.12

Updates the requirements on [iced_graphics](https://github.com/iced-rs/iced) to permit the latest version.
- [Release notes](https://github.com/iced-rs/iced/releases)
- [Changelog](https://github.com/iced-rs/iced/blob/master/CHANGELOG.md)
- [Commits](iced-rs/iced@0.9.0...0.12.0)

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

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

Cargo.toml

@@ -20,7 +20,7 @@ members = [".", "examples/split-chart"]
 plotters = { version = "0.3", default_features = false }
 plotters-backend = "0.3"
 iced_widget = { version = "0.1", features = ["canvas"] }
-iced_graphics = "0.9"
+iced_graphics = "0.12"
 once_cell = "1"
 
 [dev-dependencies]