build(deps): update rust-ini requirement from ^0.20 to ^0.21 in /libDF

Updates the requirements on [rust-ini](https://github.com/zonyitoo/rust-ini) to permit the latest version.
- [Release notes](https://github.com/zonyitoo/rust-ini/releases)
- [Commits](zonyitoo/rust-ini@v0.20.0...v0.21.0)

---
updated-dependencies:
- dependency-name: rust-ini
  dependency-type: direct:production
...

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

Author: dependabot[bot]

libDF/Cargo.toml

@@ -119,7 +119,7 @@ ogg = { version = "^0.8", optional = true }
 claxon = { version = "^0.4", optional = true }
 env_logger = { version = "0.11", optional = true }
 clap = { version = "4.0", optional = true, features = ["derive"] }
-rust-ini = { version = "^0.20", optional = true }
+rust-ini = { version = "^0.21", optional = true }
 tract-core = { version = "^0.21.0", optional = true }
 tract-onnx = { version = "^0.21.0", optional = true }
 tract-pulse = { version = "^0.21.0", optional = true }