build: bump serde from 1.0.228 to 1.0.229 in /silkd

[dependabot]

Bumps serde from 1.0.228 to 1.0.229.

Release notes

Sourced from serde's releases.

v1.0.229

• Update to syn 3

Commits

• 7fc3b4c Release 1.0.229
• 6d6e9a1 Merge pull request #3085 from dtolnay/syn3
• 6dec3b7 Update to syn 3
• cfe6692 Resolve mut_mut pedantic clippy lint
• 1023d07 Update actions/upload-artifact@v6 -> v7
• dd682c2 Update actions/checkout@v6 -> v7
• 5f0f18b Update ui test suite to nightly-2026-06-01
• 63a1498 Regenerate stderr with trybuild normalization fixes
• fa7da4a Fix unused_features warning
• 6b1a178 Unpin CI miri toolchain
• Additional commits viewable in compare view

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[CMGS]

Applied in 318d270 (serde 1.0.229).

Verified with the rest of the round: make go-lint (10x 0 issues.), make go-test, make lint, make test, the silkd suite on native linux/arm64, and a bare-metal round on a Ryzen 7 9700X (16c/60G) — sandboxd e2e x3 PASS with 16/16 smoke steps, warm-claim p50/p90 unchanged at 0.3ms across an A/B/A/B bench, and 84 clean full boots (0 failed units).

[dependabot]

OK, I won't notify you again about this release, but will get in touch when a new version is available. If you'd rather skip all updates until the next major or minor version, let me know by commenting @dependabot ignore this major version or @dependabot ignore this minor version. You can also ignore all major, minor, or patch releases for a dependency by adding an ignore condition with the desired update_types to your config file.

If you change your mind, just re-open this PR and I'll resolve any conflicts on it.