build(deps): bump serde-json-wasm in /contracts/pricefeed (#123)

Bumps [serde-json-wasm](https://github.com/CosmWasm/serde-json-wasm) from 0.4.1 to 0.5.2.
- [Changelog](https://github.com/CosmWasm/serde-json-wasm/blob/v0.5.2/CHANGELOG.md)
- [Commits](CosmWasm/serde-json-wasm@v0.4.1...v0.5.2)

---
updated-dependencies:
- dependency-name: serde-json-wasm
  dependency-type: indirect
...

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