Update kotlin to v1.6.0

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
org.jetbrains.kotlinx:kotlinx-serialization-protobuf	1.5.1 -> 1.6.0
org.jetbrains.kotlinx:kotlinx-serialization-json	1.5.1 -> 1.6.0
org.jetbrains.kotlinx:kotlinx-serialization-core	1.5.1 -> 1.6.0

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Release Notes

Kotlin/kotlinx.serialization (org.jetbrains.kotlinx:kotlinx-serialization-protobuf)

v1.6.0

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This release contains all features and bugfixes from 1.6.0-RC plus some bugfixes on its own (see below).
Kotlin 1.9.0 is used as a default, while 1.9.10 is also supported.

Bugfixes

• Improve error messages from Json parser (#​2406)
• Mark @​SerialName, @​Required and @​Transient with @​MustBeDocumented (#​2407)
• Ensure that no additional files except java compiler output get into multi-release jar (#​2405)
• Fix enums with negative numbers in protobuf not serializing & de-serializing (#​2400) (thanks to Doğaç Eldenk)

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Configuration

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