build(deps): update axum requirement from 0.7 to 0.8

Updates the requirements on [axum](https://github.com/tokio-rs/axum) to permit the latest version.
- [Release notes](https://github.com/tokio-rs/axum/releases)
- [Changelog](https://github.com/tokio-rs/axum/blob/main/CHANGELOG.md)
- [Commits](https://github.com/tokio-rs/axum/commits

)

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

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

examples/axum/Cargo.toml

@@ -3,7 +3,7 @@ name = "axum-example"
 edition = "2021"
 
 [dependencies]
-axum = "0.7"
+axum = "0.8"
 tokio = "1"
 
 [target.'cfg(target_os = "hermit")'.dependencies]