Update axum requirement from 0.7.1 to 0.8.1

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] <[email protected]>

springtime-web-axum/Cargo.toml

@@ -16,7 +16,7 @@ default = ["derive"]
 derive = ["springtime-web-axum-derive"]
 
 [dependencies]
-axum = "0.7.1"
+axum = "0.8.1"
 config = "0.15.4"
 downcast = "0.11.0"
 futures = "0.3.29"