chore(deps): bump pyo3 to 0.27 and simplify ffi interfaces

[vvanglro]

Upgrade PyO3 from 0.20.1 to 0.27.2 and infer from 0.15.0 to 0.19.0. Replace legacy reference types with Bound APIs and owned handles. Accept &str directly in from_path to leverage automatic Python-to-Rust string conversion. Switch blocking calls from allow_threads to detach for explicit GIL release during file operations. Add lint configuration for PyPy-specific cfg flags.

[gemini-code-assist]

Summary of Changes

Hello @vvanglro, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request delivers a substantial update to the project's Python-Rust interface by upgrading key dependencies, PyO3 and infer, to their latest versions. The changes streamline the Foreign Function Interface (FFI) by adopting modern PyO3 patterns, simplifying string conversions, and refining GIL management for blocking calls. Additionally, it introduces a linting rule to improve PyPy compatibility, ensuring the project remains robust across different Python runtimes.

Highlights

• PyO3 and Infer Crate Upgrades: The pyo3 crate has been significantly bumped from version 0.20.1 to 0.27.2, and the infer crate from 0.15.0 to 0.19.0, bringing in the latest features and improvements from these core dependencies.
• Modernized FFI Interfaces: Legacy PyO3 reference types have been replaced with the new Bound APIs and owned handles, aligning the codebase with current best practices for Python-Rust interoperability.
• Simplified String Handling: The from_path function now directly accepts &str for file paths, leveraging PyO3's automatic Python-to-Rust string conversion and simplifying the interface.
• Improved GIL Management: Blocking operations in from_bytes and from_path now use _py.detach() instead of _py.allow_threads(), providing more explicit and potentially safer Global Interpreter Lock (GIL) release during file operations.
• PyPy Compatibility Linting: A new lint configuration has been added to Cargo.toml to warn about unexpected_cfgs specifically for cfg(PyPy), enhancing compatibility and maintainability for PyPy environments.

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[gemini-code-assist]

Code Review

This pull request upgrades PyO3 and infer, and refactors the FFI interface. The changes are mostly correct, but I've found critical issues related to memory safety when using py.detach(). The provided closures capture non-'static references, which can lead to use-after-free errors. I've suggested fixes that involve copying data to ensure it has a 'static lifetime. Additionally, there's a small issue with a build dependency version in Cargo.toml that should be updated.