Bump libraries for Kotlin client.

[sylwester-zielinski]

It's a libraries bump for Kotlin multiplatform client side.

Main changes are Ktor bump to 3.0.1 and Kotlin to 2.0.21.
Adapts to new API as it has been done here.

There was one issue with runTest function in Coroutine.kt file for JS after Kotlin bump.
This function had internal modifier in commonTest and no usage so I assumed it's a legacy thing and deleted it.

Kotlin Committee:
@dr4ke616 @karismann @Zomzog @andrewemery @4brunu @yutaka0m @stefankoppier @e5l

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[e5l]

@sylwester-zielinski, thanks for the PR. LGTM

[4brunu]

Thanks for creating this PR.
Looks good to me.
CI Failure is not related to this PR.