Update serde_yaml requirement from 0.8 to 0.9

Updates the requirements on [serde_yaml](https://github.com/dtolnay/serde-yaml) to permit the latest version.
- [Release notes](https://github.com/dtolnay/serde-yaml/releases)
- [Commits](dtolnay/serde-yaml@0.8.0...0.9.32)

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

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

pingora-core/Cargo.toml

@@ -39,7 +39,7 @@ nix = "0.24"
 structopt = "0.3"
 once_cell = { workspace = true }
 serde = { version = "1.0", features = ["derive"] }
-serde_yaml = "0.8"
+serde_yaml = "0.9"
 libc = "0.2.70"
 chrono = { version = "0.4", features = ["alloc"], default-features = false }
 thread_local = "1.0"