Update cargo_toml requirement from 0.20.5 to 0.21.0

Updates the requirements on [cargo_toml](https://gitlab.com/lib.rs/cargo_toml) to permit the latest version.
- [Commits](https://gitlab.com/lib.rs/cargo_toml/commits/main)

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

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

code-generator/Cargo.toml

@@ -14,5 +14,5 @@ k8s-openapi = { version = "~0", features = ["latest"] }
 serde_yaml = { version = "0.9.34" }
 glob = { version = "0.3.1" }
 itertools = { version = "0.13.0" }
-cargo_toml = { version = "0.20.5", features = ["features"] }
+cargo_toml = { version = "0.21.0", features = ["features"] }
 toml = {version = "0.8.14"}