Update kotlin monorepo to v1.7.21

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
org.jetbrains.kotlin.plugin.serialization (source)	1.7.20 -> 1.7.21
org.jetbrains.kotlin.jvm (source)	1.7.20 -> 1.7.21

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