Resolve compilation warnings

[martin-azpillaga]

I also receive some warnings during compilation:

The 'org.jetbrains.kotlin.platform.*' plugins are deprecated and will no longer be available in Kotlin 1.4.
Please migrate the project to the 'org.jetbrains.kotlin.multiplatform' plugin.
See: https://kotlinlang.org/docs/reference/building-mpp-with-gradle.html

I think that they can be solved using:

plugins {
    kotlin("jvm")
}

rather than:

plugins {
    id("org.jetbrains.kotlin.jvm")
}

Thanks for your work and help.