Update Rust crate serde to v1.0.206

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
serde (source)	dependencies	patch	1.0.205 -> 1.0.206

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Release Notes

serde-rs/serde (serde)

### [`v1.0.206`](https://togithub.com/serde-rs/serde/releases/tag/v1.0.206) [Compare Source](https://togithub.com/serde-rs/serde/compare/v1.0.205...v1.0.206) - Improve support for `flatten` attribute inside of enums ([#​2567](https://togithub.com/serde-rs/serde/issues/2567), thanks [@​Mingun](https://togithub.com/Mingun))

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Configuration

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