Update Cargo.lock to force Rust widget rebuild

[rileyseaburg]

Summary

Update Cargo.lock dependencies to force CircleCI cache invalidation and trigger a fresh Rust build.

Problem

The previous cache bust (v2 → v3) didn't work because the cache key uses {{ checksum "ext/widget_renderer/Cargo.lock" }} and that file hadn't changed. The checksum was the same, so CircleCI restored the old cached library.

Solution

Run cargo update to update dependencies to latest versions, which changes Cargo.lock and invalidates the cache.

Updated dependencies

• itoa 1.0.15 → 1.0.16
• libc 0.2.177 → 0.2.178
• ryu 1.0.20 → 1.0.21
• serde_json 1.0.145 → 1.0.146
• syn 2.0.110 → 2.0.111

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