Update taffy requirement from 0.7 to 0.8

Updates the requirements on [taffy](https://github.com/DioxusLabs/taffy) to permit the latest version.
- [Release notes](https://github.com/DioxusLabs/taffy/releases)
- [Changelog](https://github.com/DioxusLabs/taffy/blob/main/CHANGELOG.md)
- [Commits](DioxusLabs/taffy@v0.7.0...v0.8.3)

---
updated-dependencies:
- dependency-name: taffy
  dependency-version: 0.8.3
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

crates/bevy_ui/Cargo.toml

@@ -33,7 +33,7 @@ bevy_platform = { path = "../bevy_platform", version = "0.17.0-dev", default-fea
 ] }
 
 # other
-taffy = { version = "0.7" }
+taffy = { version = "0.8" }
 serde = { version = "1", features = ["derive"], optional = true }
 uuid = { version = "1.1", features = ["v4"], optional = true }
 thiserror = { version = "2", default-features = false }