Update axum requirement from 0.6.0 to 0.7.1

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](tokio-rs/axum@axum-v0.6.0...axum-v0.7.1)

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

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

Cargo.toml

@@ -38,6 +38,6 @@ features = [
 
 [dev-dependencies]
 assert_matches = "1.5.0"
-axum = "0.6.0"
+axum = "0.7.1"
 metrics-exporter-prometheus = "0.12.0"
 tokio = { version = "1.20.1", features = ["full"] }