chore(deps): update rust crate schemars to 0.8.21

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
schemars (source)	workspace.dependencies	patch	0.8.19 -> 0.8.21

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Release Notes

GREsau/schemars (schemars)

v0.8.21

Compare Source

Fixed:

• Fix null default not being set on generated schemas (https://github.com/GREsau/schemars/issues/295 / https://github.com/GREsau/schemars/pull/296)

v0.8.20

Compare Source

Fixed:

• Revert unintentional change in behaviour when combining default and required attributes (https://github.com/GREsau/schemars/issues/292)

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Configuration

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[codspeed-hq]

CodSpeed Performance Report

Merging #2997 will not alter performance

_{Comparing renovate/schemars-0.x (33f982a) with main (e52084a)}

Summary

✅ 92 untouched benchmarks