bump for 50.0.1 + changelog (#15520)

* bump for 50.0.1 + changelog

* Silence new nightly clippy clone_on_copy lint (#15419)

* Silence new nightly clippy clone_on_copy lint

Recent Rust nightly (1.99.0-nightly) started reporting
`clippy::clone_on_copy` for the `clone` call that `pyo3::pyclass`'s
`from_py_object` option generates, which fails the nightly CI job with
`-D warnings`. The four affected pyclasses are all `Copy` enums in
`serialization.rs`, so allow the lint for that module. An item-level
`allow` does not help here because the offending code lives in a
sibling impl block emitted by the macro.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018qbYhmwr3z7r3znpg14n2k

* Link pyo3 issue for the clippy allow

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018qbYhmwr3z7r3znpg14n2k

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Co-authored-by: Claude <noreply@anthropic.com>

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Co-authored-by: Claude <noreply@anthropic.com>