Bump serde_json from 1.0.61 to 1.0.64

Bumps [serde_json](https://github.com/serde-rs/json) from 1.0.61 to 1.0.64.
- [Release notes](https://github.com/serde-rs/json/releases)
- [Commits](serde-rs/json@v1.0.61...v1.0.64)

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